How to picks the backspace n the enter?

why does the backspace and the enter of my loptop cannot funcioning?

If they don't work after trying them in a number of different programs, it's likely that the keys aren't making contact. Look at the the manual that came with the laptop for how to clean the keys. On most you can pop them off and clean them. Make sure and do it with it turned off and use alcohol, not water if needed. It has to be completely dry before turning it back on.