Removed tonsil stone from soft palate now i have a canker sore on the spot and redness around it. no other symptoms. should i worry? how do i cure it?

No: This is probably nothing more than the healing process starting. It should get better daily. If things get worse, or if healing doesn't improve in a week, get it re examined!

No cure needed: It should heal on its own within a week or two, if it is actually a canker sore.

Time: The tissue is irritated. Give it time to heal. The redness and canker sore should be healed within two weeks.