A vertical line in the middle of my Acer P221w monitor

See attached link NEC P221W BK MultiSync P221W BK user manual

http://www.driverscape.com/download/acer-p221w

Heare you can finde drivers .

Probably the resolution is incorrect for the extended monitor.

Look "underneath" the bottom-centre of the display.
Look for a "silver" coloured button at bottom-right of the face.
Look for a "rocker" switch along the right-side edge.

Or, ask a pre-teen girl who wants to update her Facebook. :-)

disconnect the monitor from the system and check if all the pins of the cable are not damaged. if not damaged, then check the device manager for exclamation marks, try and reinstall the drivers
steps to open device manager;
click Start select Run type Devmgmt.msc press Enter

read the manual it should tell you

If you need further help, reach me via phone at https://www.6ya.com/expert/joel_63c670a84e9f6a97

You should have some buttons on the front of the monitor, one of them is probrably a menue button which should allow you to adjust alot of the monitors settings from within there.

You can always download a manual by googling your monitors model number for exact instructions.

1680x1050.
It also depends on the video card how high the resolution can go.
That's the max resolution though.
Here's the complete specs for your monitor.
Have a good day!

It has a 3 year warranty.

Since you have surely looked, it isn't held on with exposed screws.
Check to make sure that the rounded area that allows tilting is not part of the case but appears to be separable.
Most that are removable are held by a tongue and a fairly obvious release tab.

if you can't remove the base, just place the monitor in the carton on good padding and upside down.
Fill and cushion the sides well, mark the carton with 'This side up' and an arrow and hope there are no malicious handlers on the trip.

I've shipped numerous monitors of different sizes and types and have lost none of them to shipping damage.