Restore data from partition Ive installed windows on?

You can try using a utility to see what it can find in terms of recoverable files. It won't be able to recover them ALL because you undoubtedly overwrote some of them when you installed Windows. But if you want to try, then read on ...

1) Download and install the trial version of GetDataBack for NTFS from Runtime Software in MS Windows.
2) Run GetDataBack and select the option to find Deleted files.
3) When done, browse the filesystem in the app to see if your directories and files were found. If so, view some to confirm the contents are intact.
4) If they are, you will have to purchase GetDataBack to do the actual recovery. You won't have to reinstall it; instead, they will email you an activation code which you can use to turn on the recovery feature.
5) You will have to recover the files to a different drive -- you can't recover files to the same partition. SO, you will have to hook up an external drive to do the recovery.

And, last time I checked, GetDataBack for NTFS was $80, USD.

Your data ... your money ... your choice.