Not on an emotional level - that seems impossible sometimes.
Rather physically. Remind yourself you‘re attached to a body. Remind yourself you can experience the world around you.
For instance, splash your face with cold water, multiple times. If you‘re cold, let warm water run over your wrists, it warms you up quick.
Put yourself out there in the (chilly) wind and/or sun. Either open a window and stick your head out or - if you can get yourself to do that - really go outside for a walk. Could be a quick five minute stroll or an extensive one. Also helps clearing your head of any noise.
Reconnect with nature while you‘re at it. Just touch your environment. Do it. Touch the leaves you pass by, touch the tree branches, step into puddles, pick up flowers, blow a dandelion. If you have the opportunity, (if you‘re living near a farm or similar) pet animals.
Those things usually help me regain a bit of positivity or any (positive) feeling of being human at all.
Hope this helps, slumps suck, but there‘s better days ahead. After all flowers need rain to grow, no? 💐