If my personal brand has been damaged/neglected where should I start to make changes to improve it?

For old relations :

Take one relation/person at a time and try to fix it ..discuss with them politely during comfortable time and tell your feelings and listen to their views and based on discussion ,think where you need to change or where they are right/wrong..Healthy discussions solves majority of human relationship problems ...

If above method is not working with 1-2 persons i.e. they are not listening to you,healthy discussion is not happening etc etc then i'll say that just leave them and move on or just ignore them and move forward to fix other relation..

For new relation:

you can always make new friends ...Start some good conversation ..whenever you meet someone (in your building/ lift / office) just say hi/hello else atleast nod and smile.. if you are comfortable then start with weather/ current issue etc and if person is responding well then you can start good conversation..

All the best ...

H