User manual for brother sewing machine lx-3125

hi Lori.
at this link you will see some diagrams that might help you out.

diagram of threading brother LX 3125 sewing machine Google Search
you could also try this one.
diagram of threading brother LX 3125 sewing machine Google Search

Your machine is probably out of adjustment. You can probably take it in for service, however, the repair cost may be as much as a new machine.

...

Your owner's manual should have instructions. Download the manual here and then enlarge the picture on your computer screen to see it better. I believe it shows to put a drop of oil and spread it around the outside edge of the hook (see pg.41 for picture of the hook). Then there are five spots to put a drop of oil on the take-up lever and needle bar (pg.39). Basically, they are spots where the metal parts rub against other metal parts. Gently rotate your handwheel toward you and watch where things move and apply a drop of oil. The last spot is where the needlebar rubs when you raise the presser foot. Here's a manual to download:

https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&ved=0CB8QFjAAahUKEwjn342p5-fGAhVBMIgKHUsfC3E&url=http%3A%2F%2Fwww.brother-usa.com%2FModelDocuments%2FConsumer%2FUsers%2520Manual%2FUM_LX_3125_ENES_1612.PDF&ei=HuqrVefYLMHgoATLvqyIBw&usg=AFQjCNGhQ30zoj93NdlMH7lzNHr2J21zQQ&bvm=bv.98197061,d.cGU&cad=rja

...

This sounds like a job for a repair shop.
Gears break, and all such things can be wrong.

Cheers,
Kelly
San Diego, CA
Embroidery Services

it's possible that the timing needs to be checked at a sewing machine shop.

you have to contact a brother dealer about the part

the best thing to do is have the machine checked at a sewing machine shop

Here is a link to download your manual for your sewing machine for free.

http://www.brother-usa.com/manuals/default.aspx?PGID=3&R3ModelID=LX3125

Scroll down towards the bottom of the page and click on where it says "English/Spanish manual" and save it to your pc.

Go to www.brother-usa.com and under support for home sewing and embroidery, you will be able to download a free manual.

sounds like you have the bobbin clutch disengaged. Check to make sure you have flipped it back to sewing mode.