Hi, Chriss Hadow and welcome to our forum,
We do not deal with password type issues on the forum here, so we regret we are unable to assist you other than as follows.
We are sure your request is genuine, but alas you will understand the difficulty we face and hopefully understand why this blanket decision (which does not reflect on you in any way) has been taken.
Maybe the following will assist you:
1 Any person with an Administrative status account on your computer can reset, alter, add or remove the log in /password credentials, so it would be wise to contact the old works/firm and ask for the log in credentials to be reset. However if you know another person who has an Administrative level account then you could ask them for assistance.
2 When the password(s) were originally set up it is usual to create a password reset disk either on a disc or memory stick, so you could have a search around to see if you can locate it.
3 If it's only information from the computer files, you are after, then the easiest way to access them, is to use one of the back up copies of the files that were made (they will usually be kept on tape, external hard drive, Memory sticks, other computers, DVD's etc).
4 You could consult a local competent computer technician, take your computer to her/him together with documentary proof of ownership and a letter from the original owner ( the old works/firm) confirming you are entitled to legitimate access to the machine, and ask for a quotation for the information to be retrieved.
Further than that we are afraid we are not willing to go.