As above, you need to get energy into her at short regular intervals, now, if you don't have twin lamb drench or glucose, get some honey, treacle, or sugar solution into her asap. Also if you have a vitamin drench give her this, there is vit B12 in twin lamb drench, if she is likely to be calcium deficient then would recommend getting some calciject (calcium with magnesium ) into her asap.
We have managed to save an old ewe that we hadn't realised was pregnant with drenches, soaked sugar beet, she was down for some 2 weeks before lambing, and it then took a few days after lambing for her to recover and be up on her feet again. Try different feeds to tempt her to eat, if she isn't ruminating you can buy a rumen stimulant, or you can steal cud from another sheep to help get her ruminating again.
Good luck