So I I tried to install windows 7 on an old laptop to retrieve some very important files. So to save the files, I opened command prompt in the installation setup then tried to make an unallocated space by shrinking volume on my disk drive to make new partition. (This laptop doesn't turn on unless plugged in.) While shrinking the volume my laptop suddenly turned off and now it can't detect any USB bootables nor my HDD.
Time to remove the drive and install it in a USB dock or enclosure.
Since the files are "very important" please consider sending the drive out for professional recovery.
otherwise step 1 would be to make an image of the drive and then run recovery operations on the image; preserving the original drive 'as-is' in case it really needs professional recovery. You'll need someplace of equal size as the HDD to store ehe image and then another place to store the recovered files.
In the future, important files need to be backed up which means having more then one copy of them and each copy would be on a different device (CD, DVD, Flash Drive, USB drive, another pc, cloud...)