Hi,
thanks for giving JabRef a chance!
it seems like that for some reason the file field contains latex symbols:
It should be sufficient to replace the
$\backslash$ with a normal backslash, \ then JabRef should be able to parse it so that it looks like a normal windows path. Otherwise, the syntax is correct.
The path should look like C:/ or C:\. Although windows normally use backslashes, it should also work with forward slashes.
I advise copying the bib file before making any changes. You can use JabRef’s inbuilt search and replace function Edit → Find and Replace. There you have the option to limit this to the file field.