Will Allah hold me accountable for abandoning prayer due to the laziness and lethargy resulting from antidepressant medications, and will my prayer be accepted if I pray sitting?

No one has an excuse to abandon prayer as long as their mind is sound. Abandoning the obligatory prayer is a grave sin, so it is not permissible to abandon it due to laziness. One must remind oneself of the punishment for abandoning prayer and associate with righteous people. Prayer while sitting is not permissible for the obligatory prayers when one is able to stand. However, for supererogatory prayers, it is permissible to sit, but one receives half the reward of one who stands. If standing causes extreme hardship, then sitting is permissible for the obligatory prayer.