HELP! MY COMPUTER IS INFECTED WITH RANSOMWARE!

I have no idea what to do now, I just hope that there is a way to make my files accessible again… I cannot open them anymore. File extensions were changed, besides, my desktop wallpaper has been changed and it shows a message in english and russian languages. I have sent an email to cyber criminals, they want me to pay them.. i dn’t have money. i just hope that there is a way to recover my files! Please help me to decrypt .xtbl !