I had the same problem with my shower earlier this month, didn't have time to find a hardware shop, so I poured a shit load of bleach straight down the drain and left it from morning until evening, then flushed it out - it worked!
Try to get a plunger, an old school but effective way - if you can't find one, run some water, put you hand over the plug and make a cup shape with your palm, then push up and down quickly, making sure to keep a seal (water helps with this). It's not ideal, but it can help - I'm not taking the piss, by the way!
Hardware shops carry that stuff
I had the same problem with my shower earlier this month, didn't have time to find a hardware shop, so I poured a shit load of bleach straight down the drain and left it from morning until evening, then flushed it out - it worked!
Try to get a plunger, an old school but effective way - if you can't find one, run some water, put you hand over the plug and make a cup shape with your palm, then push up and down quickly, making sure to keep a seal (water helps with this). It's not ideal, but it can help - I'm not taking the piss, by the way!