thanks @jodee. another person also warned me about this problem (with screenshots) but i still don't know what can i do about it.
The site's hosting service is provided by 1freehosting (as far as i know they are solid but) maybe this problem is related with them.
But if anybody can tell me what can i do about this i'll appreciate it.
By the way i learned a new way for making graphics for my games thanks to a site once @mammooth mentioned, and that means there won't be any bad pixel art for my next games :) that's good news for your eyes and also a relief for real pixel artists.
Here is the site and what i did is below (i tried to stay loyal to my original pixel art character)2dgameartforprogrammers.blogspot.comebrar2013-03-28 21:56:05