This will probably solve the issue
-download the update manually and install after downloaded
Download details: SQL Server 2005 SP3
If that does not help and same issue, that would probably mean that the service is not started.
Go to start, run and type services.msc and hit enter
-go down list and look for SQLEXpress and right click on it and choose properties
Use the dropdown box and select manual and the click the start button and then Apply
Now try to run the update again
If still not working, post back with any details tha tmay have happened when trying