Memory ?

[CGB]

Hello to you all,
I am having a spot of bother with my Key remote key fob, it began to be a bit slow when i operated it to lock the car. So, I thought it was time to change to battery, I duly purchased the correct type of battery and set about changing it. all went well and I fitted the new part. Feeling pleased I went out to try things fully expecting all to be fine, however, it was not to be and nothing worked. Someone suggested the fob might have a memory and maybe I had lost it. Does anybody know or have any ideas please.?
Chris.