This is a very simple fix and it’s a problem everyone will come across at least once while using 3Ds max. It’s a very common problem even at university level; I’m usually telling people this simple fix.
Example: If I try and select the torus, I can’t. This is because as you can see at the bottom there is a lock which is highlighted. This means that the object selected is locked and you can’t select anything else. Just press the space bar to turn this on/off. Now you should be able to select the torus.
Another problem might be that when you use the move tool you can’t see the x y and x axis when selecting an object. Press X and then you should be able to see the helper. The 2 images bellow can explain better.