failed random 2 years ago and cant get back in

hope someone can help me. 2 years ago i failed radom drug screen and the company i drove for terminated me. my bosses fought hard for me but i was out. they wouldnt put me through sap program nor could i afford it on my own. was my understanding that i had to either go through sap or leave truck driving for 2 years.
well my 2 years are about up but everywhere i turn im told no. ive been waiting for this for 2 years and i wish i knew where to turn. im not sure if i should give up and look for another career or what. all i know is i miss it badly. im the first to admit i made a mistake and ive paid for it for 2 years.
my work record other than radom is great. i worked for 10 years same company. 1 moving violation the whole time. heck i was a trainer for them.
any help or direction would be greatly appreciated. just hoping somthing can be done.

thank you all ahead of time