Every device has a Vendor and Device id associated with it. If you can find this ID, you can find the manufacturer. In Windows it's easy to find the vendor and device id.

1. Open Device Manager (Control Panel>System>Hardware>Device Manager)
2. The hardware whose drivers are missing will appear as Unknown device, so it's easier to locate the device.
3. Right click on the unknown device and click on Properties.
4. Under the Properties window click on Details tab and select Device Instance Id from the drop down box.
5. You should see a code similar to this

PCI\VEN_8086&DEV_27DC&SUBSYS_30868086
&REV_01\4&1E46F438&0&40F0
6. The portion of the code highlighted in RED is the Vendor ID and the portion highlighted in BLUE is the Device ID. In this example:

Vendor ID = 8086
Device ID = 27DC
7. Once you have obtained both the IDs, proceed to PCI Database. There you can either search for the vendor from the vendor ID or directly get information about the device along with the vendor name by searching with the device ID.