I have no drivers for Satellite A135-S4427,

You can download it here for free:

http://www.manualowl.com/p/Toshiba/Satellite-A135-S4427/Manual/165450

Go to toshiba website:http://www.csd.toshiba.com/cgi-bin/tais/support/jsp/modelContent.jsp?ct=DL&os=&category=&moid=1598555&rpn=PSAD0U&modelFilter=A135-S4427&selCategory=2756709&selFamily=1073768663

All available drivers for your laptops model can be found here : http://www.csd.toshiba.com/cgi-bin/tais/support/jsp/modelContent.jsp?ct=SB&os=&category=&moid=1598555&rpn=PSAD0U&modelFilter=A135-S4427&selCategory=2756709&selFamily=1073768663
hope this was helpful.

You can download any/all the Windows XP device drivers for your model laptop from the Toshiba WEB site from their download page. Make sure you enter the model of your laptop so you can get the correct drivers. Please click on this link: -
http://www.csd.toshiba.com/cgi-bin/tais/support/jsp/home.jsp
http://blitware.com/adpages/driverfetch/manufacturer/?manufacturer=Toshiba&gclid=CMOVxNCBx6ACFSgnawodoHNGbA

Follow the illustrated guide below and be sure to make a copy of it......

http://www.irisvista.com/tech/laptops/toshiba-satellite-a135/remove-mainboard-1.htm

Try the following link

http://www.irisvista.com/tech/laptops/toshiba-satellite-a135/remove-mainboard-1.htm

The Toshiba Satellite A135 series stock keyboard is not backlit, and that model only supports one type of non-backlit keyboard, which is interchangeable with several other Satellite series. Here is some extended info on the keyboard for your model: http://www.machinaelectronics.com/store/buypart/Toshiba_Satellite_A135_S4427/K000044100

Check out this link for XP drivers http://support.toshiba-tro.de/tools/Satellite/sl30/xp/display-psl30e-xp-820300.zip

From the link below (53 Download Files) you will have to Refine your Search by choosing which Operating System you have on your laptop as well as Category, otherwise at the bottom of that list you can click on the page number/next to find it.

Now correct me if I am wrong, You are looking for the sound driver for your Toshiba Satellite A135-S4427, if so they're there.

good luck,

Bastian

Try this:

http://www.realtek.com/downloads/downloadsView.aspx?Langid=1&PNid=13&PFid=5&Level=5&Conn=4&DownTypeID=3&GetDown=false

or this:

http://www.realtek.com/downloads/downloadsView.aspx?Langid=1&PNid=7&PFid=7&Level=5&Conn=4&DownTypeID=3&GetDown=false#RTL8100E/RTL8101E/RTL8102E-GR/RTL8103E(L)%3Cbr%3ERTL8102E(L)/RTL8101E