To fix this, you can try to cross the corner part.

It happens that the wallpaper is torn in the corners of the room. This happens either at the nerve angles, or if you used thin paper wallpapers — soaked in glue, they are torn very quickly. To fix this, you can try to cross the corner part. The torn panel must be carefully removed, and the new one is glued so that the edge of the wallpaper bloces it at least 10 cm. If the gap occurred due to the irregularity of the wall, make a small incision in which insert a piece of wallpaper, and glue all the parts to the wall