My key got broken and need a replacement

On hills my car rolls back

Ive done lots of home made mods cold air intake straight off ac blower and other thing but hit vac line on booter one night so repaced it ran bad after ther at time did not know it had what i guess is a chack valve in it got. One few days later know car wont start did start one time but that was it could i have hurt my booter an could that have anything with it not starting but that one time

When the battery dies, why does the windows stop working after I replaced the battery?

i turn the key everything works inside lights radio etc. but wont turn the ingine on