1)as you told that you are out of doha for one year i will dismiss any chance of sponsorship transfer/change because it only means that you are working in doha and you have a valid id.
2)If you are out of doha for one year.i guess that you canceled your previous visa and went out. in this case you cannot come back before two years.
3)if you have not canceled your visa and just went to another country to join another job,your previous visa was automatically canceled after 6 months prior of your departure from doha, unless your exit permit was extended by the sponsor for 6 months more.in this case you cannot come back before two years.
4)if you are out of doha for one year with a extended exit permit of this period you must come back doha after this period to keep your visa and id valid,if you do not your visa will be canceled and there will be no chance of transfer and change of your visa as it was canceled, so you have to get a new one.and you cannot get it before two years.
5)if you have the phone number of your previous sponsor contact with him directly and request him for a NOC that will define specifically that he have no objection if you come back doha and you can work with another company.after getting this NOC there is a chance that immigration department will agree to issue a new visa for you.
please consider following matters
1)as you told that you are out of doha for one year i will dismiss any chance of sponsorship transfer/change because it only means that you are working in doha and you have a valid id.
2)If you are out of doha for one year.i guess that you canceled your previous visa and went out. in this case you cannot come back before two years.
3)if you have not canceled your visa and just went to another country to join another job,your previous visa was automatically canceled after 6 months prior of your departure from doha, unless your exit permit was extended by the sponsor for 6 months more.in this case you cannot come back before two years.
4)if you are out of doha for one year with a extended exit permit of this period you must come back doha after this period to keep your visa and id valid,if you do not your visa will be canceled and there will be no chance of transfer and change of your visa as it was canceled, so you have to get a new one.and you cannot get it before two years.
5)if you have the phone number of your previous sponsor contact with him directly and request him for a NOC that will define specifically that he have no objection if you come back doha and you can work with another company.after getting this NOC there is a chance that immigration department will agree to issue a new visa for you.
hope you all the best.