My printer is dcp-165c... and have continuous ink ..there is an error that says please close ink cover....what will i do????

Machine Error 46 indicates that the ink absorber pad is full and needs replacing. You will need an engineer to replace this.
If your machine is out of warranty, please contact Brother Customer Service:

7777 North Brother Blvd.
Bartlett, Tennessee 38133
1-877-BROTHER (877-276-8437)
901-379-1215 (fax)
M-F, 9:00am to 8:00pm Eastern Time

http://www.nodevice.com/user_manual/brother/Multifunctional/dcp-165c.html
This user manual can help you

Check the locked on the right side of the ink cover if it is aligned well on the small sensor button.

remove the ink cartridges & replace them again after cleaning the electrical contacts

The cover for the Ink cartirdges has a switch on it. Try opening the cover, then close it again, the switch may be jammed. Try repeating several times if it does not do anything. If it is still the same case, then someting from the inside of the printer has caused the failure.

it said "close ink cover".

UNIT UNABLE 50

Your black printhead is blocked.
The printhead is deep inside the printer and has to be taken out by the expert and cleaned with the help of 'steam' and hot water. This is because not using the printer for a long time. or using low grade refill inks.
Please select new cartridge only if you are inserting a new cartridge or fully refilled cartridge. Otherwise use old cartridge option. Brother printer has a mechanical sensor and not the electronic chip in the ink cartridges.
After inserting the old used cartridge if you choose 'new cart' option it will show the "Full" ink. You can still print from the exhausted ink cart after covering the sensor in the middle by a piece of paper in emergency.

controller pcb maybe faulty.