My Console Application window can't display letters from other alphabets(e.g russian) when I run the program. It's just displaying question marks in place of them. Please help if you can.

Set the encoding to something that includes your characters:

Console.OutputEncoding = Encoding.UTF8

Sorry, the console is only 8-bit, so UTF16 not an option.

Then use a font which encodes and contains the characters. Change the properties of the cmd.exe to use Consolas font, for example.

check with your unicode and utf encoding formats,
also check if there can be culture that can be filtered.