Downgrade to Win7 From Win8 on a win 8based laptop?

I tried doing this and lost the hidden partition.

I will suggest you to remove the hard drive with Win 8. Buy a new hard drive and install win 7 there. So in case you need win 8 again, change the hard drive.

Just install Classicshell.net
http://www.classicshell.net/
You can go to desktop automatically at logon. It puts back the start button and search functions.
You then add freeware to replace any software that opens in Windows 8 full screen, such as Adobe Reader to open in a Window. With Classicshell.net and no full-screen opening software (just change the "open with"), you will hardly know it is Windows 8, but you can still get to the "apps" screen when you want it.

If you have restore DVD with your laptop then you should directory install win7. Format C: and install win7. When you want to go back win8 then use your restore dvd.

Don't.
Installing Win7 is probably going to remove your Win8 recovery partition, and your UEFI partition and your Microsoft Reserved partition, and… Yeah, Win8 has a lot of partitions.

Instead, upgrade to Win8.1. It's free from the Microsoft store (which is a tile on your Win8 Metro Start screen). You can set Win8.1 to go to the desktop, and then it's almost like Win7 except that you right click the start button instead of left clicking it… And bonus you can still get to the Metro Apps.