Is Windows Search configured on the server to index file contents for the file types you want to search? It sounds like it is. By default, some file types only have their file properties indexed.
- Open Indexing Options from the Start menu.
- Click Advanced.
- Switch to the ‘File Types’ tab.
- Click the file type you want to index.
- Check ‘Index Properties and File Contents’.
- Click OK.
The index will be rebuilt, which can obviously take time depending on the number of files. If you still can’t get it to work, test it in a lab environment and try to establish what is different in production.