I have downloaded a load of apps for my iphone and for some reason when i plugged my iphone into my laptop it took them all off my mobile an put them onto my app page on itunes so how can i get them back onto the phone as some of them are paid apps?

If you've paid for them before, you can download them again from the App Store and you won't be charged. Not sure why it would have wiped them from your phone though - do you normally synchronise with a different computer?

When you're iPhones connected to itunes, click on it on the left hand bar and selectbthe apps tab from the top row. Make sure sync apps is ticked. (it usually isn't). You can then select which apps you want to sync back.