I'm 43 years young and I had my tubes tied 20 years ago. And 4 months ago my period stop can I be pregnant

Hello and thank you for choosing EmpowHer,
The chance of pregnancy will depend on the nature of the surgery you had. There are 3 different surgical procedures for a tubal ligation. They can be cut, and stapled. The third procedure is to have them damaged so that scar tissue creates a blockage. The third method allows for a greater chance of pregnancy to occur over time. If the tubes do not fully seal, or partially heal over time it allows passage to uterus. Since your procedure was 20 years ago, there is some possibility that your fallopian tubes have somehow healed enough to support pregnancy.
But be aware that you could also be experiencing an ectopic pregnancy which is very dangerous. In either case, I suggest that you have your fallopian tubes examined and also have a pregnancy test to know what is really going on. You may want to have a pap smear/pelvic exam to determine if something else besides pregnancy could be causing the sudden lack of periods.
Faith