Trying to recover some deleted photographs

I have accidentally deleted some photos (grandchildren, special events etc) that I thought were backed up on my slave drive. I used Active File Recovery to undelete them, but I cannot open them. Irfanview says "cannot display header". Tony

Try using PhotoRec, which is designed for "digital picture and file recovery": it's not guaranteed to work but at least it's free. Image Recall may be even better: it costs £24.99, but there's a demo version. Programs that will try to reconstruct damaged image files include Pix Recovery and EasyRecovery Pro.