I screw up the database and schema of my rails app, what should I do to rebuild database from my migration files?

I screw up the database and schema of my rails app, what should I do to
rebuild database from my migration files?

My code is all OK, and it has all and only the migrations from which I
want my database to be create, as I re-run them one bye one..
How should I do this.
my schema file is also screwed up.
thanks