English equivalent of the Italian "Mannaggia!", "Che peccato!"

What is the English expression or exclamation to refer to something that has gone wrong or a missed opportunity, or something that we could have done better than we actually did?

I'm specifically wondering about an English equivalent of the Italian interjections “Mannaggia!” and “Che peccato!”

Solution 1:

To Shyam's list (alas, my bad, and oops) I would add

alas and alack - a bit more dramatic than the already-dramatic alas
what a pity or what a shame
oh no or uh oh
d'oh (for fans of The Simpsons)
shucks or aw, shucks (esp. to signify embarrassment on the part of a simple or unsophisticated person)
woe is me (in mock despair)

To add a sense of disgust as well as disappointment, one could use

rats
drat
phooey
yuck

Of course, you have onomatopoeic words like argh, ugh, hrmph, or bleah and all manner of profanity. Some euphemisms have come into their own as "dictionary words" as well, like

dagnabbit, doggone it, goshdarnit, or goldurnit (for goddammit)
jiminy cricket, jiminy Christmas, or jeepers (for Jesus Christ)
shoot (for shit)