My stylus 300 digital camera goes off after a few seconds and powers off, with lens retracting. why??

check the batteries. does it take double AA? if it does, try the energizer lithium or rechargeable AAs.

All digital camera have an auto off feature to save on power. if you want your camera to stay on longer just change the setting from the cameras menu system.

your batteries are probably extremely low. even if you are using a rechargable battery, those die slowly over time so you probably just need to grab a new battery shouldnt run you more than fifty bucks. good luck

Sounds like it is time to charge the battery.