the installation process of MySQL on windows are very simple as other software you need just configure them and they works.

but somebody after migrating their mysql server to 5.5.8 confuse that their old database is now gone but it’s not  you need to do something to get back

go to

C:\ProgramData\MySQL\MySQL Server 5.1\data

the programdata folder commonly hidden in any version of windows.

you find their some folder cut them all you want to recover.

note that don’t copy the file mainly in data folder just like err pid or log because they are configuration file and the configuration of mysql 5.1 and 5.8 both are different

after copy the folder  go to

C:\ProgramData\MySQL\MySQL Server 5.5\data

paste here the folder

restart mysql and all database is now in your hands.