The first place to look is the School Details table to check your year start and end dates. If you go to Admin>Config>Core Setup>School.
The Year Start is the first day students are back in school that academic year, and the Year End is the last day of student registers. Click on Edit tab at the top of this table and amend the dates if they are incorrect.
Then go to Home>Dashboard to check the attendance figures, as well as a student attendance tab to view the attendance weekly breakdown.
If this has not resolved he issue, please email firstname.lastname@example.org requesting us to look into this for you.