A) There is no reset button. As with any computer that has Windows, press the CTRL key, ALT key, and DELete key, AT THE SAME TIME to restart the computer.
B) To restart, is to Reboot. Rebooting isn't going to help in this case.
(If it does it will be temporary)
You have a problem with the graphics chipset, or the Video Cable, or the Display Assembly.
Diagnose to see which one it is.
1) Laptop OFF, monitor OFF, attach a VGA monitor to the laptop.
Connect to the VGA port on the Back of the laptop.
[ It is named External display (VGA) port, by Acer.
This is an example of a VGA Cable, and a VGA port (Connector)http://en.wikipedia.org/wiki/VGA_connector
The external VGA monitor can be a CRT type (Looks like a small TV), or a flat LCD screen monitor that has a VGA cable.
2) Turn the monitor on. If a CRT type allow it to warm up.
3) Turn the laptop on.
By default the display should show on the external VGA monitor.
Press, and hold down on the Fn key, and at the same time tap once on the F5 key.
(Fn key is on the bottom row of keys on the Keyboard. Second key over from the Left.
F5 key is on the top row )
No display on the external VGA monitor?
There are at least 3 display options.
1) Internal monitor of laptop ONLY
2) Internal monitor of laptop AND external VGA monitor
3) External VGA monitor ONLY
You may have to tap more than once.
(Hold the Fn key down, and tap on the F5 key)
C) IF, the display does NOT show up on the external VGA monitor, you have a graphics chipset problem.
Chip and Chipset are slang terms for I.C.
The graphics chipset's proper name is GPU. Graphics Processing Unit,http://en.wikipedia.org/wiki/GPU
The GPU for the Acer Aspire 5100 series of Notebook PC's, is an
ATI Radeon Xpress 1100.
It is soldered directly to the motherboard, therefore it is
Integrated Graphics. (NOT a Graphics adapter Card that is removable)http://en.wikipedia.org/wiki/Comparison_of_ATI_Chipsets
If the graphics chipset is bad, the easiest, and most cost effective solution, may be to simply replace the motherboard. More on this at the end of the solution.
D) IF, the display DOES show up on the external VGA monitor, the problem is the Video Cable, or in the Display Assembly.
The Video Cable is termed LVDS Cable by Acer.
Low-Voltage Differential Signaling Cable.
The Middle Cover is the thin strip of plastic that has the LED indicator lights, and Power On button in it, located above the Keyboard.
Removing this cover allows access to the motherboard side, of the LVDS Cable.
Check this connection to make sure it is tight.
The LVDS Cable also connects to the Back of the LCD screen.
The Display Assembly must be partially disassembled, in order to access this connection.
Check this connection to make sure it is tight.
With the Middle Cover removed observe the motherboard side of the LVDS Cable, and it's sheath. (Outside cover of the cable)
See if there is any obvious signs of damage. The LVDS cable routes under the left Hinge. Normal opening, and closing of the laptop may damage the sheath.
If the sheath if the LVDS Cable shows damage, the tiny, thin wires inside the cable may be damaged also. (Stretched/Broken)
If damage is shown the LVDS Cable should be removed, and a continuity test of the wires in the cable, should be performed with a multimeter.
This may be accomplished with an economical multimeter, set to Ohm's. (Symbol is the Omega symbol)
An economical multimeter can be purchased for around $8 to $12.
Analog, or digital is fine.
Or you could take the cable to a computer repair shop, and have them test it for you.http://www.cdsparts.com/p-2292-new-acer-aspire-one-532h-ao532h-nav50-led-lcd-cable-50sas02005.aspx
The Display Assembly (LCD Module) consists of the;
1) The LCD Bezel:
The thin plastic frame that is in front of the LCD screen, and surrounds the LCD screen. Resembles a picture frame.
2) Screen Inverter:
3) LCD Panel Brackets:
Metal brackets that attach to the sides of the LCD Panel's screen frame.
(Screen Frame; metal frame that surrounds the LCD screen. The LCD screen is composed of layers, and the metal screen frame holds them in place)
Also includes the Hinges.
For the Acer Aspire 5100 series of Notebook PC's, the Backlight is a CCFL. Cold Cathode Fluorescent Lamp
5) LCD Screen:
6) LCD Module Cover:
The top cover of the laptop
An LCD screen does not produce light. It needs an additional light source.
A Backlight is the additional light source.
A Backlight can be a CCFL, or a series of LED lights.
As stated the Aspire 5100 series uses a CCFL.
A CCFL is a Cold Cathode Fluorescent Lamp.
Similar to Fluorescent lighting used in homes, and businesses, but on a MUCH smaller scale.http://www.laptopz.com/acer-aspire-5100-laptop-lcd-ccfl-backlight-lamp-154-wxga-p-10364.html
[ Average size is 2mm Thick x 334mm Long.
In inches it is approximately a little larger than 1/16th of an inch Thick, and a little over 13 inches Long.
It is located INSIDE the Screen Frame, and next to the LCD panel's layers. The Screen Frame comes apart by removing screws. The side of the Screen Frame, that the Backlight is mounted next to, is removed to access the Backlight.
HOWEVER, the LCD screen (Panel) is composed of layers. These layers are set in a specific pattern, and are held there by the Screen Frame.
If the correct method is Not used when replacing a Backlight, there could be a chance the screen layers of the LCD screen may move, and this would render the LCD screen unusable ]
A qualified professional is called on to perform this repair.
The Screen Inverter converts power (Electricity) from the laptop, for the Backlight, and LCD screen.
90 PERCENT OF THE TIME the fault is a bad Inverter.
Testing a screen inverter is done with a sensitive multimeter. A tool most do not have. Or a known to be good compatible screen Inverter is used as a test tool.
Due to this, the economical cost of a screen Inverter, and ease of replacing, the screen Inverter is usually replaced.
IF, this does not repair the problem, then the problem is a bad LCD screen.
More information in a Comment.