YOU SAID:

I would if I cold, but I can't so I shan't

INTO JAPANESE

風邪をひいたらいいけど、できないのでいけない

BACK INTO ENGLISH

I wish I had a cold, but I can't because I can't

INTO JAPANESE

風邪を引いていたらいいのに、できないのでできません

BACK INTO ENGLISH

I wish I had a cold, but I can't because I can't