Not sure you can, but it is possible that the old profile still exists and you can switch back to that or retrieve data.

First type [about:profiles] in the URL/address bat to find what and where the current profile is

Then use your file manager to get there, you may see other profiles.

Copy the whole [profile] folder with existing multiple profile if there

There is a file called [profiles.ini] which dictates which profile Firefox will use.

By the way best to state which OS you are using at it gives others a better idea of where to point you.

Not sure you can, but it is possible that the old profile still exists and you can switch back to that or retrieve data. First type [about:profiles] in the URL/address bat to find what and where the current profile is Then use your file manager to get there, you may see other profiles. Copy the whole [profile] folder with existing multiple profile if there There is a file called [profiles.ini] which dictates which profile Firefox will use. By the way best to state which OS you are using at it gives others a better idea of where to point you.

The hard disk in my pc had failed. I had to replace it with a new one and so I installed Firefox on new pc. So, there is no profile saved locally in the computer. The system is Windows 11.

If the data is really really important you can get the disk analysed for recovery example:

https://www.dataclinic.co.uk/faq/

If the data is really really important you can get the disk analysed for recovery example: https://www.dataclinic.co.uk/faq/

Thanks for your reply. I was able to salvage the required data folder from the failing harddisk. Only the OS partition was corrupt, other data were intact only. I got all my firefox data.

I also enabled onedrive backup so I don't do this again. Issue resolved.