The serial number is located on the bottom of the notebook on a white label and is 22 characters long. Older notebooks may have serial numbers that start with “91″ and will be 20 characters. The label will look like this. Go here to enter your serial number for warranty information.
If your computer turns on: Choose About This Mac from the Apple Menu; Double-click the version text, for example “Version 10.4.” Your computer’s serial number now appears where the version text had been. Go here to find your warranty information.
If your computer does not turn on: Turn your computer over and remove the battery. There should be a sticker on the inside of the battery compartment, not on the battery itself, which has the serial number on it (usually marked S/N). This picture is of a MacBook, if you have a MacBook Pro, an iBook, or a PowerBook, it will look slightly different but the concept is the same. Newer MacBook Pro models have a serial number on the bottom of the case. Go here to find your warranty information.
Step 1: On the underside of your laptop look for a sticker that has your “Serial Number” and “Model Number.” Your serial number is located here.
Step 2: Your model number is located here. Asus computers come with a standard one year warranty. With the serial and model number, call Asus Technical Support Service at the toll-free line (1-888-678-3688) for questions about your warranty. If there are more questions about Asus and warranties, visit here.
On the underside of your laptop look for a sticker that has your “Service Tag.” It should look something like this. Your Service Tag is a unique five- to seven- digit alphanumeric (letter and number) code. Enter it here for your warranty information.
HP or Compaq
On the underside of your laptop look for a sticker that has your “Serial Number” and “Product Number.” It should look something like this. You will need both of these numbers for your warranty information. Enter both of these here.
IBM or Lenovo
For the warranty check you will need the “Serial Number” and “Product Number” from the underside of your laptop. Once you have these, enter them here.
Look on the bottom of the laptop for the model and serial numbers. They should look like this. Enter both of these here for more information.
Option 1: On the underside of your laptop look for a sticker that has your “Serial Number,” “Product Code,” “Service Tag,” and “Model Name.” Sony laptop series and model numbers begin with the letters “PCG” or “VGN” and are located on a small label on the frame around the LCD display or above the keyboard. The label is normally the same color as the case with contrasting letters. The model number is typically a more detailed variation of the serial number – both numbers can be obtained from the same label. NOTE: Do not use the “Model” listed on the grey label on the back of the computer as this will not provide the correct information. The stickers on the Vaio computer come in two different fashions. The first type is the combination label located on the bottom of the computer. This label has all model information combined onto one whtie barcode label that looks like this.
Option 2: On other models, the Product Code and Serial Number are located on a small white barcode label and the Service Tag (only on some models) is located on a second label on the bottom of the computer or behind the battery. These labels look like the picture. With your information, visit here for information about the warranty.