I caused this problem messing with the Python executables in /usr/bin, trying to get eclipse PyDev working with the current python version. I downloaded the Python 3.7.3 to /usr/local/bin, then linked python, python3, python3.7, etc., in /usr/bin to the new 3.7 versions. I also deleted some python2 pyXXXXX files whose names included the word "text".

I am running Mint 18.3 Cinnamon. All my personal files are backed up to other computers and external drives on the network, including all my dot files. I can boot the system. It comes up to the login prompt and splash screen. After I log in, the screen goes blank/black, except for Computer, Trash, Home, an external drive that has an old timeshift backup on it. The cursor is also visible, and functioning. The icons respond to clicking on them.

I have never restored from timeshift, and the version of the kernel on the computer has been updated from the timeshift backup on the drive. Not sure whether I can, or how to run timeshift from the command line.

I can't bring up a terminal. I can ssh in from another computer. I can also log in as root booting in recovery mode.

Any ideas how to get the desktop back?

An inelegant brute-force solution, but it worked:
- logged in by ssh from another computer
- one by one, copied py* files from the timeshift backup on the external drive to /usr/bin
- changed all symbolic links in /usr/bin back to their former values
- rebooted