This sounds like you have two textframes on top of each other.
The first one, with your TOC in in, is on top of the other one, your regular text. When you click on the "TOC" story, you can move your cursor through it -- but not any further than the end of the TOC.
The underlying cause of your con-fused frames and overlapping stories is that InDesign cannot create just a Table of Contents -- it always needs to be a separate story, and thus it always needs a set of frames of its own. Very annoying.
Jongware is most likely correct. TOC is ALWAYS a separate story, so the cursor cannot move out of it by using the arrow keys, but when I read the rest of the problem description I had the thought that some of your frames were either locked or or on the master page (that's pretty unlikely as they would show on multiple pages if they were), so you might want to open up the layers panel and expand the layers, then look for lock icons on each page.