login security

We have Windows XP Home Edition. There are four family members that use the computer. Three of the members have limited access, while the other member (me) has administrator access. The problem is, the other day, I went to change my password everything seemed to go fine. However, the computer had been going very slow that day & giving me troubles. I logged out. Later that day I went to log in & enter my password & the computer is stating that it is an invalid password. I only use one of two passwords & I have tried them both along with several other tries. My questions are: 1) Is there anyway to get into my login to change that password? 2) Or, is there anyway to go into one of the other users & change their status to admin? Any help with this matter is greatly appreciated! Thanks! Sher