Hello!
I am finished with creating my typeface in Fontlab 7 and now I have issues with exported file.
The typeface has 8 files but only ONE has issues, letter "s" is missing in preview and also in Photoshop when I try to use it. As if something is overlapping it(I removed overlaps in Fontlab) and it is still visible but just barely.
Second issue I am having: when selecting style from the typeface drop down menu in graphic design software, Regular or Regular Italic is missing.
I would appreciate some help?

Comments
As for the Regular / Regular Italic not showing, it depends on the software (Word and Adobe apps do it differently) and might be a Style Linking problem, which is solved in Font Info > Instances. A screenshot might help again.
Simple check: open the glyph. Double-click on the vector outline. Shift-arrow to move it 10 units in any direction. Is there another copy underneath it?
You can securely attach the file with problems.
Thank you Thomas that did it!
In Font info>Instances there is nothing, no information.
Yes, I had to change some info, name Italics just that and manually delete font from OS before new installation. Thank you Igor!
[Note that the FL ‘Master name’ is entirely arbitrary and not used to generate any font name data. You can call masters whatever you like.]
In answer to your second question, yes, you can call a style Extended, but note that that has implications elsewhere in the naming, because of the different way in which software recognises ‘families’. So in OpenType, Extended would be one member of the StOrient family, but in a 4-style family (regular, italic, bold, bold italic) it would also constitute a separate family from StOrient non-extended. You set the latter as what FL calls ‘Style group’.