。
I've been unable to attend school for a whole week.
Literal
I [topic-は] 1-week even school [to-に] cannot-attend-continuing.
も here attached to １週間 is an emphatic 'even, as much as' — stressing that a whole week is a lot. 通えない is the negative potential of 通う ('to attend, to commute'). The ~ないでいる construction means 'remaining in a state of not [verb]ing' — a continuous inability or abstention.