Windows 7: Sound problems

No AUDIO OUTPUT DEVICE IS INSTALLED, this is the message l got on sound icone since l installed windows 7
l have download it several time these latest one it shows on panel control but not on device manager, l guess this is not really installed but l keep installing it and restat the laptop nothing happen
the sounds work only on my external speaker, but the external microphone does not work
after l installed windows 7 - l got a message on the task bar saying that PCI memory card was not installed l went to toshiba and downloaded the utilityes driver again so PCI memory is installed and nothin g wrong show on device mange, before to instal it on device manager was a notice that some 'basics card were missing'' now shows ok there but does not show realtek installed show l cannot update it or even unistal as nothing show there
this is a satellite U 300 model- used to have windows vista...
lm tired of googling it and have clue how to sort it out.. l have downloaded several other relateck or anycard sound , installed those that are accepted but nothing works on it...
please can any one help me with this issue
my email



many thanks in advance
Carlavent