how can i fix it?

Ras you don't say the make or model of your machine - but no matter because I'm not an expert on washing machines.

My standard answer for problems like the one you report is to suggest that the solenoid valve that lets the water in is broken - without water the machine will not start.

These valves are easy to change and do not cost much - you find it where the water pipe connects.

But this is all guesswork...

Good Luck...
December 2015