Recently my banana tree is acting strange. Can somebody please help me to tell me what i do wrong?
My suggestion for the reason would be nothing more complicated than a pot too small, poor soil and irregular watering. You might like to read up on a feature of the Bahamas called "banana holes" which tend to emphasize that banana plants appreciate room to spread their roots and good rich soil that along with the ability of the hole to catch water then retains water when the open planted species dry out too fast. Then as herbaceous perennials they just look after themselves.
The growing tip looks good, so it is worth re-potting to a suitably larger size, giving it rich soil and keeping it moist.
Is that some kind of a heater behind it?
Just needs some TLC, you plant looks ok for now, but being in a small pot, dry, and possibly underfed, it just needs some care. remove the old leaves repot in some shop bought compost- nothing too special and water regularly- and place somewhere with LIGHT! should bounce back within a month, and then think about placing it outside during the summer to charge it up for the winter. Most tropical plants look a bit tired at this time of year- its normal.