how can i start in xp, my pc crashed and i lost all info

What exactly happens when you try to start?

Have you tried Safe Mode Options?

To do so start tapping the F8 key repeatedly after the computer logo (or BIOS POST) before windows.

If you get the option screen first off try to "Start Last Known Good Configuration..."

If you cannot get into safe mode options:

Do you have a full version XP CD?

Or: if XP was pre-installed (OEM) do you have the Recovery disk/s?

What is the make & model of the computer?