Here are all the steps you might need to follow to actually search file contents:
1. Make sure that Windows 7 is actually going to search files with your extension, and it appears that using this list properly is important *whether or not you are looking in an indexed location*!!
a. Hit the start button and type “search” in the search box.
b. Select “Change How Windows Searches”
c. Hit “Advanced”
d. Select the “File Types” tab.
e. Make sure the file extension for the files you want to search in is on the list *and* is set to “Index Properties and File Contents” (yes, pick your jaw up off the floor). I know this appears to be for file indexing, but it does seem to make a difference on whether you find the file in non-indexed locations as well.
f. Say “Ok” and exit all the dialog boxes
2. Actually perform your search on the folder in question. Depending on some other settings you may have to type “content: spam” to find “spam” *in* the files instead of files with the word “spam” in the name. Alternately, if you press the “Alt” key when you’re exploring in the folder, you can choose “Tools / Folder Options” go to the “Search” tab and select “Always search file names and contents”.
You may run Windows Search and Indexing troubleshooter built in Windows 7 and check if it helps you fix the indexing issue. Access the link below and follow the steps to run Search and Indexing troubleshooter.
After running the Indexing troubleshooter rebuild Index and check if it helps.
To rebuild the index:
1. Open the Control Panel from the Start menu.
2. Open Indexing Options in the Control Panel.
3. Note: If Indexing Options is not available, change View by to Large icons at the top right of the Control Panel.
4. Select the Advanced button in the Indexing Options window.
5. Select Rebuild in the Troubleshooting section of the Advanced Options window.
6. Select OK when asked if you’re sure you want to re-build the search index.
If rebuilding doesn’t add the files, then you may add the folders manually to indexing and check if it helps. Access the link below and follow the steps in “How do I add or remove index locations?” to add it manually.