You really need to take it in for service if it's a laptop, Karen. No one here is going to tell a stranger how to unlock a laptop.
If it's a desktop, you can simply unplug it and remove the motherboard "coin" battery for a few seconds to reset it.
Someone may have played a practical joke by setting up a password. If it's a laptop, take it in for service. You will have to prove to them that you own it. If it's a desktop, use the battery trick to reset it.
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