I have a macbook pro which has Mojave as its operating system. I can't open Photoshop Version 4 on it.
Can you help open P'shop so I can get my photo library back ?
Photoshop version 4 was released 25 years ago and cannot run on any Mac from the last 20 years. You can subscribe to the Adobe "Photographer Plan" from US$10 to get the latest app you need (Photoshop 2021).
Not sure about photo library though. No version of Photoshop has contained a library. Could it be you were using Photoshop Elements>
No, Photoshop 4 would not have run on a Mac from 2012. I have Macs of that age. No way.
Maybe you mean CS4 (Creative Suite 4).
The thing is, Adobe really do want you to pay ongoing fees, and it's their app... they found entirely too many people bought it once and kept using it 10 years later. That's not the model the software industry want to see.
Photos is Apple software and is NOT Photoshop.
It sounds like you may have Photos from Apple, not Photoshop from Adobe. Photos was was changed under the hood and is not the same in Mojave and Catalina. A user at this site from Apple had the same issue as you and was offered several possible solutions. See if this helps: