I've had 2 mallards in my garden for 4 days in a row,I gave them duck food and even bought them a pool,but today they've not turned up,why not,anyone

Maybe they were migrating birds that stopped off to rest?

The male left her after a while,then she came round on her own fir about a week or so every day,now I've not seen her for 2 days I'd live to know why she's stopped coming round I fed her and gave her clean water I'd love to know why she's stopped coming round

They do not stay in pairs - the male will go off to join up with other males while they moult (eclipse) or to pair and breed another female - the duck may be laying somewhere she considers safe and if successful will the attempt to raise her clutch solo, once all hatched she will get them to water within 24 hours - this might be your padding pool or involve a trek to water source