Does drug resistant depression exist at all?

I'm 52 years old and I suffer from depression quite some time now.
All this started when I enter my retirement period. Whole my life I worked as a journalist. All that fuss and running, a lot of people surrounding me and a lot of people watching me. All that stopped pretty suddenly.
Of course, now, I feel useless and depressed almost all the time. So, I found out something about antidepressants and their positive affect on people’s mood, but, using them didn’t help me at all.
I tried several medications like Celexa, Opemax, Neurontin, Xanax, Seroquel but none of them could help me.
What should I do? Does something like drug resistant depression exist at all?

I know you think that you are only with this problem, but I insure you that this isn’t true.
No responding to antidepressant medications are common problems in patients with depression.
All this are leading to a fact that beside your depression you have some other health problem also.
This could be caused by several conditions but in most cases these are such as hypothyroidism and anemia.
Also, some other drugs like methyldopa, beta blockers and reserpine can cause or make present depression worse.
You should explore these possible causes of your treatment failure and try to avoid them.
I wish you luck!