Defeat to the USA has cast doubt over their prospects of advancing from Group G, but the striker is remaining positive
Clint Dempsey's goal inside the first minute on Monday night gave the African nation a mountain to climb, and though Andre Ayew equalised in the second half, a late John Brooks header inflicted a costly defeat.
Germany and Portugal are the other sides in Group G and given the strength of both nations, the clash with the Stars and Stripes was seen as a must-win clash.
Ghana must now hope they can pull off a shock victory over one or both of those nations and the USA drop points elsewhere, if they are to advance from the group as they have done at the last two World Cups.
Gyan, 28, told reporters after the game: "The gameplan went out of the window - conceding a goal inside the first 60 seconds just wasn't good enough from us.
"America weren't better than us. After that we were eager to equalise as soon as possible. We managed to get the equaliser and then we just needed to stay calm.
"We kept attacking but we've conceded a goal to another set-piece. When that happens, even though it's part of the game, you blame yourself.
"I don't think it's over. We've got another game against a top team [Germany] who have just won 4-0, and their confidence will be high, but we're capable of getting a result."
Ghana face Joachim Low's Germany on Saturday in Fortaleza.