You can try below pattern which is working:
import re
str1 = "StartString fcchwd dheoidfjewofd edeodei eddeed dd djded dojef efjefj fefije efoef; StartString wdjkndd dwojdpjf wodjojd wdjwjdm wodjow wdjwdjm ojdowj ww wdeswjd wdojwod; #jfejf /** hfhih **/ dijhfs wdjw StartString wkpwkd dokowdk djd owjidwo;"
regex = re.compile(r'(StartString.+?;)')
l = regex.findall(str1)
print(l)
Output:
C:\Users\Desktop>py x.py
['StartString fcchwd dheoidfjewofd edeodei eddeed dd djded dojef efjefj fefije efoef;', 'StartString wdjkndd dwojdpjf wodjojd wdjwjdm wodjow wdjwdjm ojdowj ww wdeswjd wdojwod;', 'StartString wkpwkd dokowdk djd owjidwo;']
solved select specific para from text file