1 Open the WinRARAPPLICATION. Click on “File” and then “Open Archive” and browse to the damaged .RAR file.
2 Press “Alt” + “R” on your keyboard. This will bring up the WinRAR repair dialog screen.
3 Designate an easy-to-find location in the “Folder to put the repaired archive” box.
4 Check the box that says, “Treat the corrupt archive as RAR.”
5 Press the “OK” button. Once it has finished repairing, a new archive will be built and placed in the location you designated.
also you can use RAR Fix Toolbox