unity startup path

[system]

how can I change the project unity uses at startup? Because of an upgrade problem from one version to another the project won't start so I need to start from another project to do this

[jonas-echterhoff]

Hold down the option/alt key while starting up Unity to bring up the project selection screen at startup.

[Julian-Glenn]

Delete or move the folder that Unity is looking in. This should make Unity start fresh.