Sometimes the Tools Panel automatically closes to give you more room, or you might have accidentally hidden the Tools Panel. You should the word "Tools" on a tab at the right-hand side of the screen, click on that tab to show the Tools Panel again:
If you can't see the Tools Panel or that Tools tab at all, you could adjust the zoom % on your screen view. Then, if necessary, adjust the zoom back to normal once you have revealed the Tools Panel.
Hopefully that helps - please let us know in the chat if you need additional help.