My swipe down feature has stopped working. When I swipe down I get the search menu (sometimes) but not the Notification Center. Have done a hard resent and still nothing.

What exactly does the screen you get look like?

When I swipe from the top, I get a search bar at the very top, and the notifications below that. If there are no Notifications to show I get the same search bar with a "No Notifications" text below it. The Notification screen will have a search bar.

If I swipe from lower than the clock at the top, I get the search screen.

Which one are you getting exactly?

You may find you've scrolled down too far below all notifications. Swipe down for notification screen. Scroll back up to top. Voila.

Those two features are activated differently. Swiping down from the top of the screen should invoke the Notification Center. To get to search, put your finger on the screen anywhere but on an icon and not at the very top, then pull down.

Hello,

Are you following the steps correctly? The steps are:

Use Notification Center

Notification Center shows your most recent alerts, like a calendar event or a missed call.

To view Notification Center, swipe down from the top of any screen, including the Lock Screen. Tap an alert in Notification Center to open it. Or tap to clear the alert.

Swipe to search

Trying to find a contact, email, or nearby restaurant? Quickly find what you’re looking for from the Home screen on your device.

Swipe down from the middle of the Home screen.

More info here:

Use Notifications on your iPhone, iPad, and iPod touch - Apple Support

Use Search on your iPhone, iPad, or iPod touch - Apple Support

Doing a full reset (holding the Power & Home button until the device shuts off) resolved the problem for me.

Then that would indicate that your not always starting high enough on the screen.

Then it's time to do some basic troubleshooting. Restart, forced restart, restore from back up, restore as new.