Should I take a day off work?

• home work business online
• online work

So yesterday i told my manager that i was gonna take a day off of work only Thursday the 14th and I looked at the schedule and it said im working on Thursday from 3:00pm to 7:00pm but I cant on that day because i have to go to this open house for college from 3:30pm-6:00pm. I don't know what to do because my manager is on vacation and shes comes to work on Wednesday from 9:00am-4:00pm. Should I call her on Wednesday?

Additional Details

i also wrote a note for her yesterday and post it on her board

Since my manager is on vacation shes is only available on Wednesday on the 13th and the other week shes off.

Should I take a day off work?