Maybe you inadvertently changed your output plugin from DirectSound to the Disk Writer??
Remember... the output plugin is always the one highlighted/selected. If you just click on a different output plugin once, you've changed it.
In case that's what's happened...
Ctrl+P for Winamp preferences > Plug-ins > Output
Select "Nullsoft DirectSound" instead of "Nullsoft Disk Writer" as your output.
*Note: if the above is what has happened, then you have been CONVERTING files into whatever Output File Location you've got set in Disk Writer configuration and you would NOT hear sound (as you indicated). So conversions have probably been taking place and you will need to delete those files.
Here's a screenshot of the Disk Writer config...
OFF-TOPIC but important...
Winamp 5.54 is Officially Released
5.54 Final is not yet offered at the Winamp.com main site yet though, but it is an official release