Endless upload with Mega 2560

Hi everyone I'm new here, so could you give me some help? I wrote a large sketch, which really works. But since today when I want to upload the sketch it compiles and starts then to upload but never ends and the Arduino don't blink. If I do the same with my Arduino Uno SMD, it works perfectly. The same thing on two other computers. The drivers are OK and the computer registered the Board. But earlier, it had also worked! So what's the problem? Is my Mega 2560 corrupted? Thank you very much

Do you get any messages at all?

Does your sketch have "!!!" in it (eg. in: "All done!!!")?

No, I don't get any failure message.

There's only printed:

Uploading....

Binary sketch size: 21350 bytes (of a 258048 byte maximum)

But it don't stop.