When i press power button it makes sound toot toot toot.and goes lens back.the lens opens little.what can i do to solve it?

Lens guide pin damaged or jamed. Try this if no luck visit service center.
follow the steps and let me know the result.
1. Ensure batteries are fully charged & clean the battery connector point in side the battery compartment.
2. Look carefully between the lens and the camera body for any sand, dirt or any damaged etc.
3. Try turning the camera with the lens facing down and shake to dislodge anything stuck
4. Try removing batteries and memory card, wait 5 minutes and refit the battery only.
5. Now turn on camera( with out card ) and see ,if working then fix the memory card & again turn on the camera. If working then fine . Otherwise format the memory card and fix back in camera again & try. Make sure before format the memory card take a back up all photos in your computer then format. If no luck then reset or restore the camera setting by pressing Menu key for 2 sec .. in not done the press both Menu & self time key for 2 - 4 sec.
i hope it will gives you success.