hello, every thing was working fine, suddenly i cant build and run on my android, and i get the bellow error, the apk also wont work, it says "this app isnt installed on your device" ,please help :(

CommandInvokationFailure: Unable to launch application. Please make sure the Android SDK is installed and is properly configured in the Editor. See the Console for more details.
C:\Program Files (x86)\Android\android-sdk\platform-tools\adb.exe -s “76f51e9a” shell am start -a android.intent.action.MAIN -c android.intent.category.LAUNCHER -f 0x10200000 -S -n “com.joybox.letterrunner/com.unity3d.player.UnityPlayerActivity”

stderr[
Security exception: Permission Denial: starting Intent { act=android.intent.action.MAIN cat=[android.intent.category.LAUNCHER] flg=0x10200000 cmp=com.joybox.letterrunner/com.unity3d.player.UnityPlayerActivity } from null (pid=17562, uid=2000) not exported from uid 11337

java.lang.SecurityException: Permission Denial: starting Intent { act=android.intent.action.MAIN cat=[android.intent.category.LAUNCHER] flg=0x10200000 cmp=com.joybox.letterrunner/com.unity3d.player.UnityPlayerActivity } from null (pid=17562, uid=2000) not exported from uid 11337
at com.android.server.wm.ActivityStackSupervisor.checkStartAnyActivityPermission(ActivityStackSupervisor.java:1089)
at com.android.server.wm.ActivityStarter.startActivity(ActivityStarter.java:789)
at com.android.server.wm.ActivityStarter.startActivity(ActivityStarter.java:588)
at com.android.server.wm.ActivityStarter.startActivityMayWait(ActivityStarter.java:1392)
at com.android.server.wm.ActivityStarter.execute(ActivityStarter.java:519)
at com.android.server.wm.ActivityTaskManagerService.startActivityAsUser(ActivityTaskManagerService.java:1091)
at com.android.server.wm.ActivityTaskManagerService.startActivityAsUser(ActivityTaskManagerService.java:1065)
at com.android.server.am.ActivityManagerService.startActivityAsUser(ActivityManagerService.java:3573)
at com.android.server.am.ActivityManagerShellCommand.runStartActivity(ActivityManagerShellCommand.java:518)
at com.android.server.am.ActivityManagerShellCommand.onCommand(ActivityManagerShellCommand.java:172)
at android.os.ShellCommand.exec(ShellCommand.java:111)
at com.android.server.am.ActivityManagerService.onShellCommand(ActivityManagerService.java:10093)
at android.os.Binder.shellCommand(Binder.java:881)
at android.os.Binder.onTransact(Binder.java:765)
at android.app.IActivityManager$Stub.onTransact(IActivityManager.java:4727)
at com.android.server.am.ActivityManagerService.onTransact(ActivityManagerService.java:2799)
at android.os.Binder.execTransactInternal(Binder.java:1021)
at android.os.Binder.execTransact(Binder.java:994)
]
stdout[
Stopping: com.joybox.letterrunner
Starting: Intent { act=android.intent.action.MAIN cat=[android.intent.category.LAUNCHER] flg=0x10200000 cmp=com.joybox.letterrunner/com.unity3d.player.UnityPlayerActivity }
]
exit code: 255
UnityEditor.Android.Command.WaitForProgramToRun (UnityEditor.Utils.Program p, UnityEditor.Android.Command+WaitingForProcessToExit waitingForProcessToExit, System.String errorMsg) (at :0)
UnityEditor.Android.Command.Run (System.Diagnostics.ProcessStartInfo psi, UnityEditor.Android.Command+WaitingForProcessToExit waitingForProcessToExit, System.String errorMsg) (at :0)
UnityEditor.Android.Command.Run (System.String command, System.String args, System.String workingdir, UnityEditor.Android.Command+WaitingForProcessToExit waitingForProcessToExit, System.String errorMsg) (at :0)
UnityEditor.Android.ADB.RunInternal (System.String command, UnityEditor.Android.Command+WaitingForProcessToExit waitingForProcessToExit, System.String errorMsg) (at :0)
UnityEditor.Android.ADB.Run (System.String command, UnityEditor.Android.Command+WaitingForProcessToExit waitingForProcessToExit, System.String errorMsg) (at :0)
UnityEditor.Android.AndroidDevice.Exec (System.String command, System.String errorMsg) (at :0)
UnityEditor.Android.AndroidDevice.Launch (System.String package, System.String activity) (at :0)
UnityEditor.Android.AndroidDeploymentTargetsExtension.StartApplication (UnityEditor.Android.AndroidBuildProperties buildProperties, UnityEditor.Android.AndroidDevice device, UnityEditor.ProgressTaskManager taskManager) (at :0)
UnityEditor.Android.AndroidDeploymentTargetsExtension+<>c__DisplayClass12_1.b__4 () (at :0)
UnityEditor.ProgressTaskManager.Run () (at <9b8dec54b88e4aa9b9661a30f7e3f61e>:0)
UnityEditor.Android.AndroidDeploymentTargetsExtension.LaunchBuildOnTarget (UnityEditor.DeploymentTargets.IDeploymentTargetsMainThreadContext context, UnityEditor.BuildProperties buildProperties, UnityEditor.DeploymentTargets.DeploymentTargetId targetId, UnityEditor.ProgressHandler progressHandler) (at :0)
UnityEditor.DeploymentTargets.DeploymentTargetManager.LaunchBuildOnTarget (UnityEditor.BuildProperties buildProperties, UnityEditor.DeploymentTargets.DeploymentTargetId targetId, UnityEditor.ProgressHandler progressHandler) (at <9b8dec54b88e4aa9b9661a30f7e3f61e>:0)
UnityEditor.PostprocessBuildPlayer+<>c__DisplayClass19_1.b__1 () (at <9b8dec54b88e4aa9b9661a30f7e3f61e>:0)
UnityEditor.ProgressTaskManager.Run () (at <9b8dec54b88e4aa9b9661a30f7e3f61e>:0)
UnityEditor.PostprocessBuildPlayer.LaunchOnTargets (UnityEditor.BuildTargetGroup targetGroup, UnityEditor.BuildTarget buildTarget, UnityEditor.Build.Reporting.BuildReport buildReport, System.Collections.Generic.List`1[T] launchTargets) (at <9b8dec54b88e4aa9b9661a30f7e3f61e>:0)
UnityEditor.Android.PostProcessAndroidPlayer.Launch (UnityEditor.BuildTarget target, System.String installPath, UnityEditor.Build.Reporting.BuildReport report) (at :0)
UnityEditor.Android.AndroidBuildPostprocessor.LaunchPlayer (UnityEditor.Modules.BuildLaunchPlayerArgs args) (at :0)
UnityEditor.PostprocessBuildPlayer.Launch (UnityEditor.BuildTargetGroup targetGroup, UnityEditor.BuildTarget buildTarget, System.String path, System.String productName, UnityEditor.BuildOptions options, UnityEditor.Build.Reporting.BuildReport buildReport) (at <9b8dec54b88e4aa9b9661a30f7e3f61e>:0)
UnityEngine.GUIUtility:ProcessEvent(Int32, IntPtr, Boolean&)

reinstalling unity solved the problem.