I'd persevere with her a bit longer before trying to foster or hand rear the piglets (each of these have their own risks)
As Robert says, the problem is with your sow, but it's not really her 'fault'.
Is she eating and drinking & pooing normally ?
Do her teats feel hot & hard or look red and painful? Could be mastitis - check her temp
If it's up an antibiotic will help clear it up - leave the piglets with her as them draining the udder will help.
You can (if you want to) use ordinary human nipple cream for breastfeeding on her teats to make her more comfortable - piglets teeth
are sharp and if it's her first litter she'll be sore
I'd check all of that to rule out any possible problems - infections post farrowing are quite common.
If she gets the all clear then give her a beer or 2 - pour it into her empty water bowl, she'll drink it
(ideally sweetheart stout, they used to give this to new mum's in hospitals to help with milk production
but anything will do at a push) this will chill her out, help her to relax and allow the piglets to feed. You might need to help them find teats and stay close to supervise things but once they start feeding and the skin toughens up she should be fine in a couple of days (you might need to repeat the beer again)
It could just be she's not a very maternal mother, but I'd give her another go anyway - I know how useless I was with my first, it takes first time mums time to learn sometimes
HTH
Karen