How do I refer to an object using a variable?

I have a large number of stationary sprites in my game and need to change a small number of them, different sprites each time, when a button is clicked.

My thoughts were to use a variable name to refer to the sprites and make the change but I cant find a way to do that. Its most likely something simple that I am completely overlooking but it has had me stumped for a couple of days.

Any help would be most appreciated.

You first add the instance variable to the object so a string 'name' then use a condition in the event sheet using the object compare instance variable.

Thank you Lionz. That's a big help.