。
My futon was pulled off me.
Literal
Futon [object-を] was-stripped.
はがされた is the passive of はがす ('to strip off / peel away'). This is an adversative passive — the speaker was negatively affected by someone removing their futon. A relatable morning scene. 布団 (futon) is the traditional Japanese bedding, laid on the floor and folded up during the day.