I have an audio circuit im building from schematics. . The schematic calls for 30nF, 220nF, 6.8nF, 22nF, 5nF, and 2.2nF capacitors ...all of which I cannot find to order. . I even converted these values into microfarads and picofarads and can't locate these parts either. . Can I substitute a closer more common value capacitor for each of these? I can send you the schematic if it helps answer my question
You must be looking in the wrong place. Go to digikey.com and enter the appropriate parametric search, and you'll find all the components you want: http://www.digikey.com/product-search/en/capacitors/ceramic-capacitors/131083?k=capacitor
Substituting capacitors used for bypassing can work just fine; typically more is better in those cases (as long as ESR and voltage rating is sufficient.) Substituting capacitors used as part of a tuned filter is much less straightforward. Thus, to answer your question, we need to know the role of each of those capacitors.
If these capacitors form filters etc. then its not a good idea to just change values. The original design specified them for a reason. You could make up the values by series/parallel connections e.g. a 5nF can be made with 2 x 10nF connected in series, a 30nF can be made with three 10nF in parallel.