I am sad

This is my first entry and I don't know where to start.  It seems everything in my life makes me sad.  I don't know how to pull out of it.  My son doesn't call I am sad, my middle son yells at me I am sad, my youngest son is not doing well in school  I am sad.   Someone at work does not say hi to me I am sad.  I get invited somewhere I am sad as no one talks to me, I don't get invited I am sad as no one thought of me.  I stay home I am alone and sad,  I go to work I am tired of it and sad.  There has to be joy out there somewhere I just can't seem to find it. 
I tried writing 5 things a day to be thankful or happy about.  I made it one day then cut it down to one a day, that lasted a week.  When I had a really bad day I just couldn't find anything to write and that made me sad so I quit.
I am just a sad, sorry excuse for a person.