1. Windows 7 --> control panel --> Indexing Options --> Advanced --> TroubleShoogint (Delete and rebuild index) --> REBUILT
2. If you do not find email you should:
- Stop windows Search service.
- cmd with Administrative rights
net stop wsearch - Set to 0 this key:
HKLM\Software\Microsoft\Windows Search\SetupCompletedSuccessfully - restart Outlook
Related article
3. About Outlook search returns No matches found you can review following KB 2769551 Microsoft article with all step by step procedures:
https://support.microsoft.com/en-us/kb/2769651