No suction in the vacuum - Dirt Devil Featherlite Bagged VacuumVacuum

Your filter may be stopped up and not allowing vacuum.
Your discharge may be blocked. In order to have vacuum you have to have a way to discharge the air.
Possibly your motor is weak

I found this info
Why is my vacuum losing suction?
A motor generates power which powers a vacuum which, in turn, creates suction to lift debris. The most common areas of suction loss are within the hose itself, the vacuum bag, clogged rollers, broken vacuum belt or a faulty gasket. All of these problems will lead directly to the vacuum cleaner losing suction.

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What Are the Causes of Vacuums Losing Suction

Some vacuums have a valve or collar near the handle that you can twist to adjust the amount of suction on the vacuum. If you open it a little it will stop sucking up your throw rugs. IF the problem is not enough vacuum then the HEPA filter may be clogged. It's usually a rectangular filter in a plastic frame. That has to be changed occasionally or the suction of the vacuum will continue to drop off.

Your vacuum may be overheating and shutting off the suction motor. Clean the cyclone assembly and the filters to see if they could be restricting the airflow.

There is a blockage somewhere.

There may be a clog where the air flows from the brush roll into the vacuum

It sounds like the roller brush is going, but the vacuum isn't working, i.e., no suction.
If you have a canister vacuum, disconnect wands from hose and place hand at end of hose. If there is suction, it's fine. If not, disconnect hose from vacuum, turn on vacuum, and hold hand to intake. If there's suction here, then the hose must be clogged; or holey hose can result in greatly reduced suction.
If it's an upright, the hose could be clogged. Or the fan broken, which would also result in no suction. It would help to know what model you have.

You have not stated which model vacuum you have. Bipass vacuum have a bipass compartment which is under drive unit. Make sure there are no cracks around housing as this is where you vacuume is created. In order to have vacuum you must have airflow, in assences suction. No air flow, no suction. If the airflow is deverted somehow suction will stop. Your filter, your bag are all sources of air flow. Clog either and you lose suction. Start with loss of air, being cracks in housing,bag or filter

I took the bottom apart and it needed a new belt and that was the problem so it's fixed.