Zikr & Dua

Reciting words of durood not established in the Hadith

Q: There is a specific durood from the elders that I have found repeatedly. Yaa rabi salli wa sallim daa e man a ba dan a laa habeebika khairil khalqi kuli hi me 

Another adds the additional line of wa barik wa salim tas leeman ka theeran ka theeraa. 

It seems as is there is an emphasis of great virtue of this specific durood. Are there any virtues or specific benefits or importance of this durood?

Turning to Allah Ta'ala in all conditions

Q: This last year has been a pretty rough patch right up until now. I used to do the the bear minimum, 5 times salaah, smile, talk good to people. 

Ramadaan time this year was the first year that I woke up for tahajud every single day, making dua and asking Allah for certain things, asking for forgiveness, etc. But I feel like none of the duas have gotten accepted. 

Even now, I still feel like my duas are not being accepted. Please assist.