My machine keeps on breaking the thread - Sewing Machines

You don't state which thread is breaking, so will assume it is the top thread.

AVOID using old or bargain bin thread!

Remove the thread.
Install a brand new needle.
ALWAYS RAISE the presser foot and rethread from the beginning.
Verify the thread path is correct.
Set the top tension to the midway point (this may need to be tweaked for your individual machine).

If it still breaks, then the thread may be catching somewhere, perhaps on the needle plate or in the bobbin area. When a needle deflects, it will sometimes strike somewhere and cause a burr or rough spot. That rough spot will then catch the thread and cause it to break or shred.

Wrap your index finger with a fine piece of scrap fabric like chiffon, nylon knit, or silk. Then run your finger around the surface (top & bottom) of the needle plate and in the bobbin area. If the fabric catches, there is a burr. Also check the hook/shuttle as this where a lot of burrs are located. If it is a small burr, it can be smoothed with a fine emery board or emery cloth. It the burr is large, the part may need to be replaced.

Sewing Machine Problem 1 Thread Breakage

Sewing Machine Thread Keeps Breaking

http://www.servicethread.com/blog/stop-industrial-sewing-thread-breaks