What to do if you forgot to perform a sajda in salah?

I think I forgot to perform sajdah when reading specific parts of the verses after reading the Quran. What happens if you don't perform the sajdah? Can a person still perform sajdah at any time to make up for it?

When you are in doubt and think you may have made a mistake, you can make two sajdas at the end of the prayer (before or after saying the final salam). This is known as sajdat al-sahu. This is not obligatory according to some scholars, which is the opinion I prefer, so even if you do not do it your prayer is still valid. If some time has passed since you prayed, you can still perform these sajdas when you remember.