Say “I didn't go,” not “I didn't went”
After didn't (did not), use the base form of the main verb.
✕ I didn't went to school.
✓ I didn't go to school.
Why?
“Did” already shows past tense. The next verb stays in its base form: go, eat, see, or buy.
- She didn't eat breakfast.
- We didn't see the movie.
- He didn't buy a ticket.