That is the problem. In most modern texts е and ё are spelled the same. If you need correct pronunciation, check academic vocabularies and language textbooks - ё should be specified there. If you doubt about inflective forms here is a good site. There ё is typed as е".
Even native speakers don't know the correct pronunciation when they meet new word in a written text. There are few particular patterns here and there but they often have exceptions. Russian spelling is not COMPLETELY phonetic, you know. Anyway English is much worse in that relation: "though tough cough and hiccough plough me through..." No?