How do I “find” my disney stocks?

Hi All
Stocks are obviously not my game – But here is the situation
I got a share of pixar stock as a gesture like, 25 years ago. it was a legit share, as a certificate.
Now 25 years later Pixar stock converted to disney stock and split a few times and Im curious how much I actually own – How do I find out and "get" my shares?
Hope this makes sense!