Access data on external drive after installing OS on it?

 
Hi! I installed Big Sur onto my external drive, because I didn't have enough space on my laptop and honestly I guess I didn't really know what it meant to install to an external drive. Now I am unable to access all the data that I had previously stored on my external drive - basically, all the documents, photos, etc that I have ever had. It appears as though the data is still there - when I go to Disk Utility, it shows 275 GB of "data" on the external drive which is about right for all my stuff, plus 15 GB of "other volume" which I'm guessing is the OS.

The data doesn't show up like it usually does on the Finder sidebar, and when I unplug the external drive and reboot with Catalina, it won't let me access the external drive at all.

Any suggestions? I don't need to keep Big Sur on the external drive, but I don't know how to get rid of it without deleting all my important files. Thanks!
 
Javier1111: I installed Big Sur onto my external drive, because I didn't have enough space on my laptop and honestly I guess I didn't really know what it meant to install to an external drive. Now I am unable to access all the data that I had previously stored on my external drive - basically, all the documents, photos, etc that I have ever had. It appears as though the data is still there - when I go to Disk Utility, it shows 275 GB of "data" on the external drive which is about right for all my stuff, plus 15 GB of "other volume" which I'm guessing is the OS. The data doesn't show up like it usually does on the Finder sidebar, and when I unplug the external drive and reboot with Catalina, it won't let me access the external drive at all. Any suggestions? I don't need to keep Big Sur on the external drive, but I don't know how to get rid of it without deleting all my important files.

And what does that have to do with MetaTrader or MQL?

Nothing! So please use a forum on Apple or some other related website to obtain information and guidance on your issue.