First of all, check whether the contents are shown correctly when you click on the text asset, if it shows no content at all, you’ll also get an empty string when you query the text asset’s text property. That’s likely the reason why you only get one line.
If you happen to encounter this problem, you’ve most-likely added characters that are not compatible with the encoding that was used to save the file. In order to solve the problem, you can either remove the characters that are not contained in the respective character set, or change the encoding when you save the file.
For example, newly created (plain) text-files on windows are often saved using ANSI encoding format by default.
Instead of searching for characters that may cause the problems, I’d simply switch the encoding to UTF-8. On windows, the built-in text editors usually allow to specify the encoding somewhere near the input field for the file name and/or the save buttons. Sometimes, the file extension dropdown also contains an extensions multiple times with additional information about the encoding that’ll be used.
UTF-8 should be able to cover the characters that you may need, and Unity should then be able to read the contents correctly.
Secondly, there are also some trivial things in your code that are redundant and/or can be improved in order to shorten the code and make it more readable.
Last but not least, please use the correct code-tags when you post code blocks, not the inline-code-tags.