This is actually more of a response to this question, but I thought would still be relevant here.
I just ran into a similar problem a few minutes ago: I could interact with the remote machine with my mouse, but all keyboard input remained inactive (this is the first time I have experienced this issue with Teamviewer).
I tried checking through multiple options, particularly "disable remote input", and nothing worked. In my case, I use Tv as a mere lazy convenience to access a machine in another room of my house so, after discovering this issue, I just decided to see if there was anything wrong on the remote machine itself. Turns out, I had no input control on that machine - not keyboard or mouse - even when I had ended the Tv session.
What ended up resolving the issue was pressing ctrl-alt-del on the remote machine to bring up the help/lock screen, and that was it! Just from that, I regained full control both locally and remotely.
I'm not sure why I hadn't thought to try that through Tv itself; I don't know if I could have solved it without going to the remote machine, but hopefully that is helpful to anyone else with this problem.
If you have a local laptop or client, can you log in, open up a text editor and see what typing remotely then gets you? – Danny Staple – 2015-01-18T12:50:24.787