Toner LCD reads Toner Empty.... the toner cartridge is new.

Locate Empty Toner Cartridge

• Turn off your Epson C900 printer and unplug it from your computer and from the electrical socket. Open the left-side panel of your C900 printer and locate the toner cartridge you want to replace. Epson has labeled each of the four cartridges.
  

Remove Old Toner Cartridge

• Stick a finger in each of the holes in the empty toner cartridge. Pinch your fingers together and then slide the cartridge out from the printer's interior.
  

Insert New Toner Cartridge

• Remove the new toner cartridge from its packaging and shake it vigorously to remix any settled toner. Take the cover off of the new cartridge by lifting it up and out to the right. Slide the new toner cartridge into the empty slot in your C900 printer. Close the left-side panel of your C900.
  

Locate Empty Toner Cartridge

• Turn off your Epson C900 printer and unplug it from your computer and from the electrical socket. Open the left-side panel of your C900 printer and locate the toner cartridge you want to replace. Epson has labeled each of the four cartridges.
  

Remove Old Toner Cartridge

• Stick a finger in each of the holes in the empty toner cartridge. Pinch your fingers together and then slide the cartridge out from the printer's interior.
  

Insert New Toner Cartridge

• Remove the new toner cartridge from its packaging and shake it vigorously to remix any settled toner. Take the cover off of the new cartridge by lifting it up and out to the right. Slide the new toner cartridge into the empty slot in your C900 printer. Close the left-side panel of your C900.
  

My friend I read your problem.F2 42 mean your copier toner cartridge is empty.when finished toner then reset chip.This toner cartridge have a chip.Or version problem.Now you buy a New toner cartridge then solve your problem.

Are you sure it was a full NEW toner cartridge?? Not an old one you had lying around.
If it was a new one the next question line goes as follows.... the machine will say in the display to "Rplace toner soon"...that dosn't mean its empty and to replace it..that means itsLOW and you should have a new toner cartridge "on-hand" because it will soon stop printing and say "REPLACE TONER". At that time the toner cartridge should be replaced, when it is installed a "fuse" on the cartridge blows and resets the toner light on the display. If you installed the toner cartridge when the display was saying "replace toner soon" you have blown the fuse in the new cartridge, now the machine has run about another 100 copies and says "replace toner"....but you now can't reset the light because the fuse is already blown because you may have replaced the cartridge too early!!! WHAT CAN YOU DO if that is the case...you can replace the fuse on the cartridge..its pretty easy to see, just replace it with another mini-fuse of the same rating written on the existing fuse..then put the cartridge in again..the fuse will blow, reset the light and away you will go. When all else fails read the operators manual.

It mean when your toner is near empty,then red light flashing.tow light is fixed or red mean toner cartridge is empty.must be replace toner cartridge.You buy a new cartridge and put in your printer then printer is OK.
you can also get better idea please read printer user guide.

I refill the toner for samsung scx4200 .Now its show toner empty replace the toner on the printer lcd. How i can slove this problem.

I have a feeling that it is a re-manufactured or compatible cartridge??
There is a fuse that needs to be replaced on this unit. it blows when the cartridge is installed to reset the machine. If the fuse has not been replaced or is defective the machine will not recognize the new unit.

If you go here:
http://www.sharpusa.com/files/cop_man_ar287_337_407.pdf
You can download the operation manual for that machine, on page 4-5 they explain how to replace the toner and have pictures showing how.
here is the text on how to replace.

Adding Toner
1 Open the front cover.
2 Pull down the toner hopper lock lever and pull the toner
hopper out slowly until it stops.
3 Tap on the top of the toner cartridge 5 times. Hold the
new toner cartridge vertically and vigorously shake it
up and down about 20 times, then invert the cartridge
and again shake it up and down about 20 times. This will
loosen the toner and allow it to flow more easily into the
toner hopper.
4 Place the new toner cartridge with the tabs in the
notches as shown.
5 Slide the toner cartridge along the guides over the toner
hopper.
6 Hold the toner cartridge with one hand while pulling on
the sealing tape to remove it.
7 Tap on the top of the toner cartridge 5 times to start the
flow of toner into the toner hopper.
l If the toner cartridge was sufficiently shaken as described in step
3, it will take about 50 seconds for the cartridge to empty. Do not
remove the cartridge until it is empty. If not empty, tap on the top
of the cartridge again until empty.
8 Slide the empty toner cartridge back along the guides
and remove it.
l The cartridge opening will be closed as it is moved back along
the guides.
9 Slide the toner hopper into the copier and return the
toner hopper lock lever into place.
10 Close the front cover.
NOTE:
Add only one cartridge of toner.

in the box with the new toner cartridge was there a credit type card to use when changing the toner to reset the toner counter?

read the instructions in the box :p

The samsung sf 5100 toner cartridge has a .05 Amps fuse in it. This gets blowed when you switch on the machine.This is used to reset the page counter and also to inform the machine that you have inserted a new toner. Now this recycled cartriges will not have this fuse and this is the reason why your machine shows TONER EMTY message! If you dont get the same rating fuse, put any fuse of the same size, insert the toner, close the door and just switch on the power and switch off immediately. Then take out the Toner cartridge and remove the fuse. Now your cartridge is ready for use.