Maybe anyway to see the QR-Codes again ? or find the File in Google Chrome Cache/Temp ?
So you replaced that text file that had the keys and QR codes? You should (a) describe exactly what you did and (b) you might be able to use a file recovery program depending on exactly how you replaced the file (e.g. opened it and pasted new contents in there vs saved over it vs dragged in trash and deleted). If you want hope of recovering it, you should stop using the computer right away so that the contents of the file have a smaller chance of being over-written.
As far as a browser cache, where you running in private mode etc? Offline copy? Online?