Unfortunately, I collected my data using different Likert scales instead of using a uniform standard scale. For example for Q1 of the questionnaire I have used a scale from 1 (Low) - 4 (High), Q2: 0 (Low) - 3 (High), Q3: 1 (Low) - 5 (High). Can I linearize the scales to one scale (e.g. 1 (low) - 4 (high)) without recollecting the data.? To be more specific, after linearizing the scales I will be able to compare mean (M) of Q1, Q2, and Q3 (my objective).
In principle you can do that. You will lose some information if your scales are of different length as you seem to imply (one of them has 5 possible answers instead of 4).
Be aware though that comparing means of Likert scales is often frowned upon for at least two reasons:
Does the mean have a real meaning here? E.g. if you have a sample of two people where one agrees and one disagrees are they on average neutral?
Likert scales are ordinal data, meaning that they can be ranked but not really manipulated in the way you would if you calculate a mean.
Mind you, the fact that it is frowned upon has not prevented many people from doing it.
Alternative ways of checking for differences after you brought the answers back to a similar scale are a chi-square test for association or if you have a small sample a Fisher exact test. These compare the distributions of the answers for two questions based on relative frequencies, and thereby avoid the problems mentioned above. On the other hand these tests ignore the order of the answers so you lose more information when you apply them.