If you're home alone and someone breaks into your home the first thing you should do is get your cellphone if possible if you don't already have it with you.
Then if possible exit the house through a back door or side door etc and call 911 and get the police to respond to the burglary.
Stay outside away from the house while waiting for the police.
If you cannot get out of the house try hiding somewhere such as in a closet behind clothes etc but try to get outside if you can.
Don't go back into the house until the police have gone through and cleared the house then they should tell you it's safe to go back in.