I have a laptop with broken internal speakers. It is out of warranty. How should I proceed in order to replace them?
Working inside laptops is very difficult if you don't have experience and the right tools.
Provided you know what you're doing, this is roughly what you'll need to do. Details regarding your specific laptop would be good.
Open the laptop up and find the speakers. Exactly how you do this will depend on what laptop you have.
Taking note of the physical size, power, impedance & connection type, look for replacements with the same specifications from electronics stores such as Jaycar.
Carefully replace the speakers, being sure they are secured well and properly connected.
Put your laptop back together, and test them out.
If you're not well versed inside laptops and with electronics, I would suggest referring to your local computer store. Some metro areas will have a specialist laptop repairer who will be better equipped to replace speakers for you.
Taking apart a laptop is simple if you have a couple small screwdrivers... it's also a pain in the butt to get it apart without breaking clips as every brand of laptop comes apart differently. I love fixing laptops though!
Step 1. Look on the manufacturer's website to find out what speakers your model has (or just skip this step and find your exact laptop for parts on ebay)
Step 2. Find those speakers on ebay or a local used computer store.
Step 3. I would have done this one for you, but you didn't say what kind of laptop it is. Google disassembly instructions for your laptop (for mine I would google "gateway md354 disassembly") Sites with images are the best.
Step 4. Using the instructions from step 3, take apart your laptop and replace the old speakers with the new speakers.
Step 5. Put the laptop back together, plug it in, and test the new speakers.
If you don't want to deal with that, you can probably find a used computer store that will do the repair cheaper than an actual computer shop.