Recently many people may have faced issue regarding upgrade skype.
Perhaps you may have seen this error “Cannot find or load Microsoft Installer while installing Skype”.
Please following this steps
Open this URL http://skype.com/go/getskype-msi This will instant download .msi file.
Signout and close your skype, if you are already logged in. This is not mandatory , but it is a good practise while upgrade software.
Click on downloaded .msi file. and follow installation process.
Step : 4
Finish. Now skype is ready with updated version.