Hi, Welcome to the Forum peeteecee !
Here are all important links:
http://lmms.io/forum/viewtopic.php?f=1&t=4740
-A few rules and useful forum instructions
 LMMS are garbled and songs play at very slow speed with garbled sound. 
One of the easiest to fix :)
Go to Edit| Settings| Click audio configuration.
Select 
SDL (Simple DirectMedia Layer as audio interface. 
OK
Shut down and reopen LMMS
Let us know the outcome :)
And if it 
diddent fix it 
please post your:
* Name of your 
Operative System (Windows/ Linux/ Mac) And subtype ('Home' 'Mint' '10.13' aso)
* lmms 
version
* hardware specification (ram & soundcard is the most important)