Fours are emblematic of stability or stagnation. Either the foundation completed and ready to be built upon, or a time which, for better or worse, there is a status quo being maintained. Reversed:
Four of Swords Reversed
Upright, this is a card of rest, recuperation or meditation - a retreat to regain health and mental sharpness. Reverse this and the man falls off his pallet. Clearly, the reversed card indicates that there is no rest, no retreat and no recuperation. The querent may want or need it, but they are not going to get it.
Four of Wands Reversed
Often called "The marriage card", this is the card of foundations laid and ready to be built upon. Reversed would indicate a blockage of this energy. The foundation is not laid or not ready - the cement, perhaps, is still wet. Certainly if a reader got this for a querent engaged to be married, the reader may want to warn the querent that they ought to postpone the wedding. Something is not solid about the relationship and the couple are not ready to marry yet. Possibly the families aren't united either. All in all, if this card is reversed, it suggests that there is quicksand underneath rather than solid stone.
Four of Cups Reversed
A card where the status quo, pleasant as it is, has become boring and the person has begun to dream of other things. The card can suggest either laziness or restlessness. Reversed, our cup of dreams spills out its temptation. But all the other cups are emptied too, and the seated dreamer is unseated. This suggests that life is not so restful and good that the person can become discontent with it. In fact, things are so emotionally empty that the dreamer can't even imagine a better life.
Four of Pentacles Reversed
Often called the Miser card the Four of Pentacles suggests that the person is hanging on to what they have, perhaps a little too hard. Reversed this card would suggest the opposite, that the person is profligate, throwing away all their money, spending it and keeping nothing for a rainy day. This might suggest a gambler or spendthrift, someone who is lending out money with abandon, or buying drinks for everyone at the bar or just buying things they don't need. Likewise, they might be ruining their health or pressing their luck.
All in all, reversed fours suggest a lack of something solid and dependable. A lack of anything reliable, be it love (Cups), money/health (Pentacles), spiritual/philosophical foundation (Wands), a way to gather up their thoughts and rest their mind (Swords).
Curious about this card when upright? Go to our Tarot Card Meanings.