I seem to have accidently deleted the 'load sample maps' option.

[Tanarex]

They are all blank and I don't know how to fix it. It might have happened when I tried to add a specially made map into the tileset. Then I tried to fix that and made things worse. So any help is appreciated.

 

[Andar]

Simply reinstall the program.

Without details on what you did we can't really help, especially as the tilesets have nothing to do with the sample maps (you are talking about the right-click on map list load function?) other than being required for them to work.
And if your tilesets are damaged, make a new project instead

 

[Windows i7]

If you have the Steam version, use "verify integrity of application files".

 

[Shaz]

Any chance you've just removed/replaced the default tilesets in the Tilesets tab?

 

[Tanarex]

Ok, I reinstalled it and got it all back.Thanks everyone for the help.