Skype shows an error message and does not start.
First you have to kill all running files of Skype i.e. running on background.
For this Open Windows Task Manager by pressing ctrl+Alt+delete at a time.
Kill any running process of Skype.exe , close task bar (do not reboot system)
Now go to Start menu and click Run.
Type %appdata% and enter. Windows File Explorer will open up, Search a folder named “Skype”, rename the folder to some other name like new_skype or old_skype.
Your call history can be reestablished as it will be in old_skype, in case.