I have Fuji s3300 and a problem occurring again and again. when I take pics its fine but when I upload it on laptop same good picture get blurred or dark after some time. same thing happens with memory card in camera. any suggestion?

Your original photo is probably the same way. The on-camera screen just doesn't have enough resolution to show you the flaws. Keep in mind, that's a tiny screen and your camera take BIG pictures. On the computer monitor, you can actually make out these changes.

Change your auto modes and take more pics of the same thing. Change exposure, aperture, and shutter timing to get better pictures.