Lenovo SL400 audio input sources lost in Vista Home Spack 2

[K7AAY]

I lost my microphone in the sound control panel, and can't record Mix
In or any other source. In the Control Panel, I select Sounds and
devices then choose Audio tabs, and there's no audio input there. The
Conexant audio driver is version 4.75.0.50 which Lenovo's website says
is the latest for my 32-bit Vista Home Basic (Spack 2).

I updated the PC Doctor software, which did not find any problems.

Two prior calls to Lenovo support blew me off, and now I am getting
the 'out of warranty' bum's rush 360 days after I received it (though
I had a 365 day warranty, but maybe time is different in Lenovo land).

Any suggestions?

Thank you all, in advance.