my friend needed to replace his battery, so he did this, and his 56k modem stopped working. He said that it stopped after the battery was replaced, so he uninstalled the modem, and when he came to reinstall it, it didn't automatically recognise the hardware, so he tried to do it through control panel, and it only gives him the option to install to com port 1 or 2, whereas before he said it was installed to com port 3. This doesn't make any sense to me, as I didn't think that the com ports were anything to do with pci devices, however I could be totally wrong. He also says that the onboard modem is disabled.

I know this is very vague, but he doesn't have much experience with computers, so he couldn't tell me too much about it, I just thought that it may be something really simple, and somebody on here might be able to spot it.

He might want to check his BIOS settings which could have reverted to default during the battery change. He should answer "Yes" to Plug and Play OS and enable "Force ESCD". These are usually unde the PCI Configuration settings depending on the BIOS.