Needle stopped penetrating my fabric

Make sure you're using the correct size needle for the fabric you're sewing.
Delicate / Very light weight.... china silk, fine lace, organza....size 8 or 9 .....Light weight taffeta, lining fabric, thin velvet, synthetic sheers size 9, 10 or 11.... Medium weight cotton nylon, crepe, knits, flannel, spandex, linen, poplin, wool, muslin size 12 or 14..... Heavy weight fleece denim, leather, vinyl upholstery fabric size 14 or 16....Very heavy weight ; heavy canvas ; thick leather size 16 or 18

According to this manual, it takes Singer needles which are probably 130/705 type:

http://homeappliance.manualsonline.com/manuals/mfg/singer/5838.html

Singer enthusiasts generally recommend using Singer needles, however, other sewists will use other brands as long as they are the same type. As for the needle size and the point, that depends on the fabric you are stitching.

All About Needles SCHMETZ Needles

Between 3 and 4

Did you take it for service? If so, the technician should be able to tell you what was wrong and what probably caused it.

If you didn't take it for service, how were you able to get it to sew again? Could be the fabric was too heavy for the needle and caused the needle to bend. It could be knocking your machine out of time. Be sure to use a heavy needle like a #16 or #18 (and for most fabrics try a "sharp" like microtex, top stitch, leather needle) and sew slowly with heavy fabric. Perhaps the fabric is too heavy for your sewing machine. I sew heavy fabric like vinyl, canvas, etc but I use an old metal mechanical machine that I can help along by turning the handwheel when the going gets tough.

All About Needles

Most likely, it has to do with incompatibility of the needle, thread, and fabric. The force of the needle penetrating the fabric multiple times is actually causing the thread to (wear &) fray and eventually break. There are needles with larger grooves that tend to protect the thread during stitching. Some may recommend a Top Stitch Needle (Home Machine Needles Superior Threads Why Topstitch? The Topstitch needle is the most common needle type used and recommended by professionals and educators. We recommend the Topstitch for piecing, quilting, embroidery, appliqu?, and construction. These needles are available in four sizes to accommodate all thread types, including metallic threads. The Topstitch needle has a larger eye and deeper groove. It is often referred as the MAGIC NEEDLE. It really does make a difference in your sewing experience.)
Why Use Topstitching Needle

Also, if the thread is a tight fit through the needle eye, it will also tear the thread. Make sure that the thread will slip easily through the eye. Go to a larger needle, instead of 90, try a 100.

Be sure to use a brand-new needle.

All About Needles

The Parts of Sewing Machine Needle

You may also consider changing the type of thread you are using. Go with a stronger thread, ie polyester, rather than cotton. Cotton will shred and break easier.

You will probably need to re-adjust the thread tension. If it is too tight, it will also break the thread. If you are using a heavier weight of thread, you will need to adjust both the upper and bobbin tension to accommodate the heavier thread.
Bobbin Tension How and Why Tension is Adjusted

If you sewing fabric that is sticky, ie vinyl, oilcloth, you should try to use a roller presser foot, a teflon presser foot, or a walking foot to help the fabric move with the feed dogs.

Sewing Heavy Fabric with NON Heavy Duty Sewing Machine SEWING IN GENERAL

Tips

Sewing through many thick layers of fabric Sactin

http://www.kollabora.com/q-a/sewing-denim-and-thick-fabric

14 Fantastic Sewing Tricks and Tips Making the World Cuter

How to Sew Upholstery DoItYourself com

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it all depends on what you are sewing 80/12 is a standard needle for heavy fabrics use a 100/16 needle

Ensure the bobbin thread is mounted on correctly and using your right hand turn the gear that makes the needle go up and down until it catches the thread.

Hi. Unthread and rethread everything, clean out any lint, and oil the machine. This, plus using the right size needle (size 16 or higher) and thread (heavy duty), should do the trick.

Let me know if this solves the problem, ok?

Good luck!

change the needle to a proper size for heavy fabric and heavy thread appropriate to the needle a number 14 or 16 needle

About the needle problem, Brother's FAQ gives the following response: 

Make sure the needle is correctly inserted with the flat side facing the back and pushed up into the machine as far as possible.

The needle could have been damaged or bent. If so replace with a new one.

Make sure the fabric is not pulled excessively when sewing. Let the feed dogs move the fabric. Do not pull the fabric.

The combination of needle size, thread size and fabric is incorrect. 
Be sure to use the correct needle and thread size for the fabric you are sewing.(example: Denim-size 16 needle and 40-50 heavy duty thread).

As for the manual, here's the link:
http://welcome.solutions.brother.com/BSC/public/files/dlf/doch000063/ps21xl55565700ug02en.pdf