Dell Latitude "BOOTMGR is missing"

Hello

Im the owner of Dell Latitude e6430.

Two days ago, I tried to reinstall my Win7 from recovery partition.

I did it before, using ctrl-F11, and everything was ok.

But this time, ive just seen "bootmgr is missing...".

I called technical support in Poland, where the guy told me that only one option, since my gyarantee is over, is to download Win10 and install it from bootable cd.

He also told me, that after this it is possible to return to Win7, using the recovery partition.

I did install Won10 and everything is fine, but i really dont like it.

So i want to return to Win7.

And this is the problem.

Recovery partition is still there with all the files on it.

But ctrl-F11 or F8 option doesnt work.

Does anybody know how to use this partition to return to Win7 in my case.

Tank you :)