These "Beep codes", as they're called, are to notify you that the Power On Self Test, or POST, has failed. The number and sequence of beeps is generally to identify which component failed, but without knowing the manufacturer, specifically the BIOS (Basic Input/Output System), it would be difficult to determine what the beep code is identifying as the problem component.
For a successful Power On Self Test to take place, the following components must be working:
BIOS (Basic Input/Output System)
CPU (Central processing Unit) or processor
PSU (Power Supply Unit)
Video Output device (Graphics card)
RAM (Random Access Memory)
If any of these fail, your computer will not power on properly, and may exhibit symptoms like what you are describing. Generally, the first step in fixing a computer that refuses to start up is to isolate components that may be causing the problem. One thing to try would be to clean the internals of your computer (Warning: be sure power is turned off to your computer before working on internals!) and to reseat components like RAM, peripheral cards (such as your graphics card), etc.. If you do not feel comfortable doing this, you may think of taking the computer in to a reputable shop- most places that are reputable would not charge or would charge very little to clean and reseat a couple components. Chances are that the problem component is either RAM or Graphics card, these components tend to fail or require service faster than others, and may also require reseating occasionally, especially in very dusty or mobile environments.
Hope this helps