Would have been better if u could offer offer any constructive solutions. I have tried asking to many many tech savvy ppl to solve this, but all it resulted was in a reply that included OS reinstall as the only option. If this post continues let us see how many reinstall replies I'll get. Have already got one (hirenjp)
Well, first I had already declared by post being an offtopic post.
Second, I did say "sorry" in advance for not putting up any constructive solution.
Thirdly, the way you put that request, "really" made me laugh!
As long as your problem is concerned, you are not getting your downloads resumed in "any" of the softwares including IDM!
So, there is only two probable causes:
Either you are downloading something from a server which doesn't support resuming from the backend itself. So no matter what software you use it wont resume.
In which case you can try downloading from sites like filehippo.com, which we are sure that it supports resuming.
Or, if your PC is not even able to resume downloading from filehippo.com, then your system is seriously effed up, and needs mending.
In this case you have to mend your PC on a serious level which includes the probability to reinstall the entire OS.
Sorry! 
