If it asks for a password it means the .rar file is encrypted just like what the akagi82 means.
It's hard to brute-force but if you believe that the file is not encrypted try to copy the RAR file to USB flash drive and then move them to another PC/laptop. Try to extract the RAR file on another PC/laptop and let's see if it's encrypted or not.
Also, I would like to know if you are using the same PC/laptop where your old wallet() is installed including the wallet.dat?
If yes maybe you can still find the wallet.dat under %appdata% even the wallet is uninstalled. Try to check the AppData folder and look for the folder of the wallet you used before then check if you can find a wallet.dat file.
Or try to brute force the RAR file using the JohnTheRipper I don't know if this will work but I heard it works on cracking encrypted RAR file.
You can find the video from here
https://www.youtube.com/watch?v=tkTgqW71r1U