Your english is fine and I understood what you want to do.
If the first letter of every line is belong to the character set [a-z] (and it looks like you want to ignore case), then it's very easy to solve.
However, if we have to take into account accented letters such as ğ then it's a lot more complicated because matlab has no concept of internationalisation. I have no idea where ğ is located in your alphabet but it's not going to be where matlab think it is.
If we assume US-ASCII alphabet only, the intruders can be detected easily:
firstletter = lower(cellfun(@(s) s(1), Cnew)).';
ldiff = sign(diff(firstletter));
outoforderrows = union(strfind(ldiff, [-1 1]), strfind(ldiff, [1 -1])) + 1
But with turkish alphabet, lower may not work correctly for a start. In addition, since matlab may have the wrong idea about the order of letters, it may tell you that some lines are out of order when they are not.