Hi lizzbeth14,
If only your Microsoft Defender Antivirus Service is in manual and not running, you should first
establish that malware is not involved.
Download a free copy of MalwareBytes from MalwareBytes.com, and run a
full scan on your
PC. Set it to "Scan for Rootkits", and allow it to clean up all that it finds.
Then, if you open the Services App and locate Microsoft Defender Antivirus Service, double
click it and attempt to start the service. First setting it to Automatic start. If you are unable to
do that, open the Registry Editor and examine the service Windefend.
Search for "regedit" and select "Run as Administrator". On the Registry Editor screen, navigate
through the following branch. Hkey_Local_Machine\System\CurrentControlSet and expand
Services. Scroll down to find WinDefend and select it. In its right pane find the sub-key
"Start". The Dword value for this key should be set for 2. If it is not, you should "modify" it
to 2. Do that by right clicking "Start" and choose "Modify". Type
2 and click OK.
Scroll up to SecurityHealthService, and find "Start" in its right pane. Its Dword should be set
for 3. If not, right click "Start" and choose "Modify". Type 3 and click OK. Exit the Registry by
retracing the steps used to navigate in. At HKLM click "File then "Exit".
If you made any modifications, Restart your PC and try Defender again.
If defender will still not start, please reply. We may have to replace WinDefend, or possibly
perform a Repair Upgrade.
Good luck, Glen