From what you said you should have a backup of the pics on your PC. When Yahoo or any service uploads pictures it does not "take" them but either draws them from your hard-drive or makes copies for their server. Never has it been that your pictures could outright be taken. If you know the name of the pictures and the extension (.gif or .jpg) just do the following

On your computer
press start (green button lower left)
menu will pop up then look for "search"
then choose "pictures,music, or video" option
type in the name of the pic with the extention (example-car.jpg)

or if you dont know the name of the pic just type in the extension either .gif,.jpg,.bmp and so forth in the search area (example- .jpg). Your computer will find all the pictures on your pc for that.

Hope it helps.