I guess that it's now confirmed since you didn't replied to my post.

Perhaps you have the "master private key" (xprv) of that watch-only wallet where the funds were swept?
If so, just use the options "File->New/Restore", set a wallet name, click next; select "Standard wallet" then "Use a master key".
Paste the xprv key there and if it's the master private key of the watch-only wallet, the balance should reflect to the new non-watch-only wallet