I have name changed to post as I don't want anyone from work realising its me 
I had a baby and have been on maternity leave, due to return next month but on reduced hours (30 instead of 39)
Previous to leaving I was well respected and managed a team of 10 or so unqualified members of staff, I was the most qualified prior to leaving.
I have been in the job for the past 11 years, and am the most senior member of staff bar management and previously trained or assisted in training all 10 staff members below me.
While I was on leave a new HR type manager was appointed as mine left.
A new job was created, a supervisor position which previously didn't exist but I had been doing. I was doing it as previous boss asked and expected me too.
Naturally I applied, however didn't get the position over 2 of the staff members I trained only last year. Both have been with the company less time, have less qualification and have 0 managerial experience.
Apparently it was a mixture of reasons, not that I had given a bad interview. A mixture of timing, amount of work needed to be put in and a number of excuses...none of which related to my work or experience etc 
The new manager wants the new staff to take on lots of extra responsibility and they will be paid higher than myself.
I really don't want to go back now as I feel really embarrassed that I have been demoted (even though I wasn't titled in the first place) and its really annoying me that less senior members of staff have been given my job while I was away 
I'm not sure what to do now, I don't want to come across as a sore looser (which I am!) but I also don't want to return to work as it's annoying me so much!