I don't think going into the BIOS Setup utility is going to help.
If the laptop was on when dropped, one or more of the Read/Write heads probably crashed right into the Platter/s.
Inside the Harddrive case are Platters. These resemble CD disks, but are made of metal, or glass.
On the top, and bottom of the Platters a magnetic media is applied. Usually a Ferrite compound. (Read Iron)
There may be 3 to 6 Platters.
EACH Platter has a Read/Write head Above it, and Below it.
The Read/Write head does just what the name applies. Reads from the Platter, and Writes to the Platter.
[The magnetic media is arranged around the Platter, very similar to how information is arranged around on a CD, or DVD disk.
It is arranged in Circles, (Tracks), and segments within the Circle (Sectors)
The magnetic media is arranged by the Read/Write head, (Write portion actually), into a series of 1's, and 0's.
1 being ON, 0 being OFF.
The 0's and 1's are converted into machine language for the computer ]
The Read/Write heads are moved back, and forth across the Platters by an Actuator Arm.
When the computer is in use, (Computer using a program for example), the Read/Write heads can move back, and forth across the Platters at Hundreds of times a Second.
The Read/Write heads are in a stationary position away from the Platters, when the computer is not on.
When the computer is on, the Read/Write heads are positioned above, and below the Platters.
They are positioned VERY close to the Platters.
(So close, that that the movement when using the computer, actually has the Read/Write heads floating on a cushion of air)
Computer on, and dropping it can cause one, or more Read/Write heads to actually crash into the Platters, and wipe some of the magnetic media OFF.
This would mean replacing the Harddrive, AND having the Restoration Disk, (CD. Also may be known as System Restore disk, or Restore Disk)
No Restoration Disk means buying a new, fresh, genuine copy of Windows, and installing it, on the new Harddrive.
On the Platters in one of the sectors, is the Boot Sector for your Windows operating system.
It could be that when the Read/Write head/s crashed on the Platter/s, that part of the Boot Sector was wiped.
It could be by a slight chance that the Harddrive has come loose. Pulled away from the interface in the laptop that it is plugged into. THAT would be a stroke of luck, but advise do not get your hopes up.
2) IBM ThinkPad X21 Service Manual (Free)http://www.tim.id.au/blog/tims-laptop-service-manuals/#toc-ibmlenovo
Click on X20. This manual covers the X20, X21, X22, X23, and X24 models.
This is a PDF file. Allow a few seconds for the first page to come up, and additional time for the file to fully download. Let the file download all the way before looking through it.
There is a way to save a copy to your computer you are using now, and burn it off to CD disk, if you wish.
If you do not know how, please post in a Comment, and I will tell you.
1040 - Hard disk drive