Alternatively, if it's been booked using the Galileo system, try www.viewtrip.com OR if using the Sabre system, try www.virtuallythere.com...

If none of those work, ask your TA to double-check the reference number. I had a similar problem recently and apparently my booking actually had two Galileo reference numbers - one issued by my TA and one issued by TG. (No, I don't understand this either but the former wouldn't work anywhere, whereas the latter, once my TA identified the problem, does at least bring something up on viewtrip...)

Still can't access my booking on TG's website but then right now, it doesn't look as if anyone can!