I uninstalled and installed Electrum again, many times, but it seems like nothing work.
Try uninstalling Electrum and moving 'Electrum' folder located in 'C:\Users\Username\AppData\Roaming\Electrum' to your desktop. Don't delete it because your wallet file is inside that folder. Try reinstalling Electrum once you do it. Both standard and standalone versions use that directory. The portable version saves additional data in the same folder as the executable so you can try running it as well.