Well then lets first move on to the other aspect and work on the backup image you created.
*I hope you transferred it to a local machine with enough storage to hold that image plus whatever gets recovered. Select a partition with enough space, my rule of thumb is to use one twice the size of the image (especially if compressed). You may elect to run Photorec on your server if transferring the image is too difficult but remember there has to be enough free space. Also note Photorec isn't for Linux only and if you don't want to or can't install it you can always use a Live CD that comes with Photorec.
Then read http://www.cgsecurity.org/wiki/PhotoRec_Step_By_Step
and pay special attention to the Photorec explanation of options
and the Photorec explanation of what file types to search for
as you do not want it to look for everything.
*Do note that for example uncompressed dumped database tables are plain text and therefore do not possess both a file footer and header so best select "plain text" as well if you need to recover any.
Then run photorec like
photorec /debug /log /path/to/image
, configure the options and file types and let it search. Depending on the size of the image, the amount of files it is able to find and the speed of your hardware this may take a while.