Having your tubes tied does not affect your periods so there may be other reasons for missed period after tubal ligation.
There is a small chance of getting pregnant after a tubal ligation (about 7 women out of 1000 who have their tubes tied will get pregnant in the first 10 years after surgery). So you need to see your Ob/Gyn for a blood pregnancy test to be 100% sure – if you are pregnant, it might be a tubal (ectopic) pregnancy which can be dangerous.
If you’re not pregnant your OB can find out why you are not regular, such as a hormone-producing ovarian cyst. If you continue to be irregular you will need more testing to find out why, but not if it’s a one-off”” episode and you go back to being regular every month.