If you are on a Windows computer, then you can do this:
Quit Skype. It's important that Skype is not running on your computer.
Go to Windows Start and in the Search/Run box type %appdata%\skype and press Enter or the OK button. This will open a window with a Skype folder. Within this folder locate a subfolder with name corresponding to your Skype name. Open this folder. You will find there a file with name main.db. It may have just have a name “main” if your PC is setup to not show extensions for known file types but you will still see description “Data Base File” in the Type column. Copy this main.db file to any location on your computer, removable storage, like e.g. an USB flash drive or CD. You will now be able to see the whole old call history by restoring the main.db database file.
