Lightbox Suddenly Not Working

I have a website with a “store bought” theme. I’ve had two lightbox plugins installed (not recently) and everything has been working fine, but all of a sudden ALL images on my website pop up in a new window. I haven’t installed any new plugins recently or made any significant changes or updates that I can think of.

After scouring the forums, I still can’t seem to find a solution that works for me.

Any help is appreciated.