What is the most probable cause of terminal freeze / unresponsive keys? I'm a relatively new Linux user (2 yrs) and am still learning to use the command line. I have used xkill and similar commands to clear a stuck process, but in some cases the keys simply don't respond and I've reverted to pulling the battery due to impatience. My question is - if the keys on the terminal are unresponsive then is it because there are processes still working, unseen by me, that have not finished? If I can't use my keyboard, then I'm unable to execute ANY command. Were I to be patient and let the software complete its tasks, would I at some point regain access to the keyboard? Or are there situations where I can never regain active keys without a reboot? Thanks.
If a terminal is frozen but not the rest of the GUI, then the first place to check is if you typed controlS, (which stops output to the terminal) and the fix for that is to type controlQ (resume output).
Because OP explicitly said "terminal", however, there is no reason to suspect the GUI.