Few of my applications start
When you restart a Mac holding command R or just option to choose a different os, that indicates a firmware password lock is present.


https://support.apple.com/en-us/HT204455
https://support.apple.com/en-us/HT203409


After reading the above, you might need a repair to regain control to wipe and reinstall or just boot to a working OS. Since your Mac is outside normal support by Apple, you might need to change the hardware yourself - perhaps removing one RAM stick per these threads:


How do Apple engineers reset EFI password on new MacBooks?
https://apple.stackexchange.com/a/121801/5472


Once that's done, you can boot to Recovery HD and reinstall the OS or erase the drive as needed.