Installed new hard drive in satellite a105 s171 no microphone signal on any applications. loaded all realtek downloads for this model from toshiba direct but still not working. speakers work fine just no mic.

From what I understand, windows 7 requires atleast 1 gb of ram to run properly, judging by your standard system specs you have 512 mb of ram. Unless you have added some ram or plan to add some to your system then no I dont believe you will be able to upgrade and run windows 7 efficiently.

you need to format drive with a os disk first and then re clone your drive

You need to replace battery with same model for toshiba laptops. Here are two links:

http://www.buy.com/prod/toshiba-satellite-a105-s171-laptop-battery-replacement/q/listingid/74232543/loc/101/214428269.html

http://www.amazon.com/Replacement-Battery-Toshiba-Satellite-A105-S171/dp/B002VBAS8K

try changing and reloading the hard disk ok

try this http://www.devicedoctor.com/

from below you can download drivers..
http://eu.computers.toshiba-europe.com/innovation/download_drivers_bios.jsp?service=EU&mode=allMachines&action=search&teddProduct=595&selShortMod=423

You downloaded the drivers? Did you install them?
After downloading, you Double-clicked on the file, then followed the instructions of the Installation Wizard?

Which driver did you install?

The RealTek LAN Driver for Windows XP (v.5.621.304.2005; 12-06-2005; 2M),

Or, the Intel PRO 10/100 Model Driver v.8.0.43.0
(v8.0.43.0; 12-18-2006; 425K)

Sure--the best one is e-bay!
Whenever I need something like this, I find it on e-bay. But if you really need to contact a company, try Spare Parts Wearhouse at 877-253-8898. National Parts Depot at 800-524-8338 may carry Toshiba parts.
I'd almost bet that the part you need is not made by Toshiba, though. Take it out and when looking for a replacement look for the mfg. name and the model.

you will need to reinstall the audio device driver.  go to toshiba.com and download the device driver for your machine.

http://drivers.softpedia.com/get/NETWORK-CARD/REALTEK/Toshiba-Satellite-A105-S4004-RealTek-LAN-Driver-5-642-914-2006.shtml

This should do it :)