I can share a success story here!
Came into undergrad (physics major) and absolutely bombed my second year. Battling with depression, the first semester of my Sophomore year saw me getting an F, three Cs and a B. Cratered my cumulative GPA down to a 2.4. (Oof.) Went and sought help at a counseling center and became very close with one of the physics professors - one whom I'd never had as a lecturer but who was known to be very open to undergrads. His help got me back and motivated and put me on the right track. I busted tail my last two years here in undergrad. It wasn't easy, especially at first. Because of my terrible performance up to that point, I didn't have the background knowledge necessary for the upper level courses, so the climb was a difficult one. But starting with the second half of my third year, I started seeing the results. Managed to get up to a 2.8 cumulative with a 3.3 major GPA. Most importantly, I found an INCREDIBLE undergrad research position doing LIGO data analysis, which I've worked in for two years now.
Two days ago I got word from my top choice school that I was accepted directly into the Ph.D program with full funding. I cried when I got the letter. Don't give up folks! People notice when you work as hard as you can and are passionate about what you do.