Hello, and welcome.
My name is ***** ***** I will be happy to help.
If the safe has not been used in a year, yes, the first thing to do would be to change the batteries, as they have most likely died. If you tell me the Manufacturer of the safe (Sentry?) and the model, plus, if you have a round or a rectangular keypad, I can give you instructions on how to change the batteries, if you've never done it before. Use only alkaline batteries or lithium for electronics (they last longer).
If you know how to do this, go ahead and install new batteries and let me know if this solves the problem, first. If not, I will continue to help.