I have just changed the background of a photo through using photoshop but now I cannot open it any other program than photoshop. How can I open it in paint or something like that?
You have by doing what you did created a Photoshop document with layers.........if this is so then open in Photoshop and under the layers heading select flatten image or merge layers and then save as a jpg ot bmp ...this will open in all or most paint programs..........
You've probably saved it as a .psd file - a type of file native to Photoshop. Open the file in Photoshop again, go to Save As and choose a file type like .jpg or .bmp
If you do this, you will automatically lose anything like layers that are only save-able in the .psd format!
This probably isn't the correct way, but this is what I always do.
Open the photo in photoshop
Print Screen
Open Paint
Press Ctrl+V to paste your Print Screen into Paint
Select the tool called "Select" and symbolised by a dotted rectangle
Drag the square over the photograph
Press Ctrl+C to Copy the image
Select File then New
Press Ctrl+V to Paste your photograph
Click File, Save As and save it.
I would recommend doing it one of the other ways in future! The reason being that you may have a lovely huge, brilliant quality photo that is "squashed" to fit on your computer screen. When you press the Print Screen, you capture it at that current screen resolution which isn't much good if you want to enlarge it at a later date...
If PhilLew's answer doesn't pan out then you've got a corrupted photoshop program. Re-install it.
You can still save the photo by downloading the free Irfan view program and its plugins. That will open .psd files and you can save it to a lot of different extensions from there.