If the password is appearing before the boot process (i.e. before you see the Windows logo), this is very likely a BIOS password. In this case, you would need to reset the CMOS for this laptop by either resetting a jumper or removing the CMOS battery itself. Since laptops are inherently compact and difficult to correct in a modular way, it is best advised that you contact IBM/Lenovo support. It is very likely you have been locked out of the system entirely.
If the password problem is occurring after Windows boots up (the Welcome screen), you may want to see this thread:
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If it is occurring prior to boot-up of the system, you should contact Lenovo/IBM. It is very unlikely that they would make any way to circumvent a...