The circuit court generally loses sentencing authority over a case once a sentence is imposed. However, you should contact an attorney regarding your PCR rights under rule 24.035.See question
One way is to search casenet. Here is a link. The problem is, not all courts will show a pending warrant, and not all municipal courts participate in casenet. Here is a link:
A second DWI is an A misdemeanor, see 577.010 RSMo.
A misdemeanors generally carry up to one year in jail and a fine of up to $2,000, however, 557.010 has specific sentencing rules for a second DWI depending on various factors and evidence in your case.
Here is section 577.010
This is definitely a case for which you should hire an attorney.See question