First of all, thank you to everyone who posted for your help and advice. It it much appreciated. Sorry I’ve taken so long to reply. In the end I had been fed up of my issues and had been ready to give up but discovered that a file I had recorded with a different software actually worked. That software wasn’t very practical for my use, but I downloaded a different version of the software I had been using (OBS > OBS Studio) and that seems to have resolved my issue. On a side-note, at some point in time me and a friend had been messing with various settings in OBS for streaming though I do not remember if this happened before or after the Sony Vegas error. We did attempt to change the settings back before I installed OBS Studio, but it did not resolve anything. Thankfully this is all over and I can go back to editing videos; case closed!