I have a dell latitude 2100 I bought frome my school.

HDP's are a Catch 22. They can be broken, but it doesn’t tend to work well and honestly usually ends with a bricked HD due to a silly error you cannot recover from when it’s committed to firmware. It uses a common 2.5” drive, so it’s not worth the risk. Take it back to IT and demand it be cleared of any old passwords, since you may not be able to do an ownership transfer under your name yet - which is REQUIRED to get Dell to help you. If you can do it, that’s going to get you in a favorable position. Grab the owner information now, keep it very safe and put it in your name when you’re 18 if you still have it. I would have considered it a condition of the sale if it was not facilitated - take that lesson with you into adult life to require the information before money changes hands with Dell, or stick to HP who doesn't care.

The password is encrypted on the drive, so the issue isn’t that it can’t be done - it can. The issue is breaking said encryption is sensitive to errors to the degree one error like a lowercase where an uppercase should be will brick the drive.

If you do this it is ultimately up to you - you’re gambling with a high chance of losing and you may not be able to absorb it and can afford to buy a new drive. It’s probably not long for this world with how old these are (3-5 year average with laptops) but it may get you by just long enough.

It may even be an OS password - you’re going to need to wipe it since school images tend to be crippled to an inch of their life anyway, so I would reload Windows and hope for the best. Testing it with a bootable Linux USB drive will also tell you, especially since the BIOS will not allow it to boot without the correct password.