Welcome to TVPaint Community forums !

I was exploring the TVP interface and I accidentally deleted the Tool Bin on the right side of the screen - the one that contains lots of custom brushes (pencils, erasers, FX brushes, etc.). I've looked everywhere, but I can't seem to get it back. Please help.

Just take a look at
windows / custom panels / tool bin

but if you completely deleted them, it could be that you have to install TVP again.
Or you can use the older ones from TVP 8.6:http://www.tvpaint.com/forum/viewtopic.php?f=11&t=3800

bytheway, you can make personal tool collections on your own