Can I use the standard single deduction amount on form 1040 line 9 (12,200) if I am filing a 2555?

YES if you are correctly filing 1040 (i.e. you are a US citizen or LPR = green-card holder, even though living elsewhere) you can take the standard deduction, and if your correct filing status was single (and not elderly or blind) for 2019 that amount is $12,200. Regardless of whether (some or all of) your income has been excluded on form 2555.

It's the same as if you were living in the US but all (or nearly all) your income was from municipal bond interest, and thus nontaxable. Or veteran's benefits. Or post-2018 alimony. (Or a combination.) You still get to take the standard deduction.

Only two groups of people can't take the standard deduction:

• people subject to US nonresident tax -- that is people who aren't citizens or LPRs, and either are living outside the US or are living in the US but don't pass the 'substantial presence test' so that for tax purposes they are treated as not living in the US. (For example many foreign students living and attending school in the US are taxed as nonresidents.)

• married people filing separately must make the same choice: either both must take the standard deduction or both must itemize.

For nearly any amount change on 1040X you need to fill out all lines 1-23, but in the situation you describe line 2 will the only one with a change in column B.