Before you can install Left 4 Dead you'll need to find the serial number that came with the program. Left 4 Dead requires that you enter a unique serial number before using it.
If you've lost your serial number, there may be a way to find it as long as Left 4 Dead is still installed. You might be able to find your Left 4 Dead serial number if you've uninstalled the program but only if the serial number information was left in the Windows Registry.
The Left 4 Dead serial number is actually more of a product key than a serial number but the terms are often used interchangeably.
Using a free product key finder program would certainly be the easiest way to find your unique Left 4 Dead serial number. Product key finder programs automatically search your computer for the product keys and serial numbers that your software programs store in the registry.
If you knew the exact registry key that stored your Left 4 Dead serial number you could find it manually but that information is usually hard to come by.
Most product key finder programs are designed to find serial numbers and product keys for operating systems like Windows XP or Windows Vista but some of them find serial numbers for several other programs too - programs like Left 4 Dead.
I've reviewed several product key finders but I haven't been able to personally confirm if any of them will find your Left 4 Dead serial number. The best key finder programs are quick to download and completely free so feel free to try them all until you find one that will show your Left 4 Dead serial.
Here are two of the more popular programs that find serial numbers and product keys:
If neither of the above programs find your Left 4 Dead serial number, give some of the other key finder programs a try from my Free Product Keyfinder Programs list. Be sure to let me know what programs did or did not find your Left 4 Dead serial so I can keep this page updated.
Important: You may have come across Left 4 Dead keygen programs or other kinds of Left 4 Dead cracks but keep in mind that these are not legal ways of obtaining serial numbers or product keys. The only legal way of installing this program is by using a valid Left 4 Dead serial number obtained through a legal purchase of the software.