Several of mine just started leafing out a week ago; some earlier, so they vary just a bit. I'd wait just a while longer. Worst case scenario is they may have died back, but should resprout from roots.

Thumb nail scratch the bark and see if you can see green. If not, snap back the dead until you get resistance and then tirm it up nicely and let time take care of it. I have about 10 that have only a little green showing here and there, but more green should come out and when time has done all it can do, I will cut out the dead and see what kine of tree/shrub I end up with.

Did the thumb nail test, at the bottom of the trunk and under the bark I did get some green, so I guess it is making and just slow and showing any signs of life.

It could have died to the ground and will sprout from the base. Has it done that yet?

Crepe myrtle's will die back when temps get below 0. We did have a big ice storm here in Louisville and I have several crepes that are struggling right now. Some are coming back from their original branches, these are the older trees. The younger trees are coming back from root and have yet to show signs of coming back from the original branches. I'm going to give them a little bit longer, but will surely have to trim them back.

Does any one have experience growing crepes from seeds?

Yes, sorta. The birds do the work for me. I have seedlings that come up every year in my borders. I have many crape myrtle trees and shrubs around my property. I get about about 5-6 every year that come up and grow from seeds in the borders that I miss when I weed or mulch. I transplanted several into pots and took to my son's house. They bloomed for the first time last year. Most were white which I expected, but one was pink. That surprised me. I thought they all would revert to the original parent which I have always thought was white.